It's better to have one person who is Level 100 at skill A and another who is Level 100 at skill B, than 75/25 and 25/75.
"Well-rounded" is another term for "mediocre."
If a person learned to become exceptionally 'talented' in one area, then he/she's more likely to replicate that same level success in a completely new area, than someone who hasn't gained that level of skill anywhere. This is because skill acquisition itself is a skill. So once you've learned what it takes to master a certain skill (i.e. you learned how to learn effectively), you can then apply it with much more ease than someone who hasn't really learned how to learn as much. This causes a sort of 'snowball-effect' outcome, where ease of skill acquisition follows a logarithmic curve of sorts rather than a linear/exponential one like most people seem to view it.
The only limiting factor on skill acquisition is choice/taste. If a particular area doesn't interest you, then why bother expending energy learning to master it, right? Doesn't mean you're not capable of it, all it means is that you didn't have to strive for greatness in that area to make it work for you. And since Jobs met Woz pretty early on, there was really no reason for him to become a master engineer thereafter. Meanwhile, Woz probably just didn't care about business/marketing, so he chose to not master it.
There are other factors that influence skill acquisition (e.g. IQ), but they don't necessarily limit it. And in order for the 'fair' view of skill acquisition to hold, there would need to be some sort of non-trainable limiting mechanism for building skills. But as of now, I'm not familiar of anything that would cause that.
The only way the "Jack of all trades; master of none" mantra holds, is if the 'Jack' never deeply learnt/'mastered' any of the subjects he's familiar with. But of course, the label "Jack of all trades" doesn't actually specify whether-or-not that's actually the case. Same for "well-rounded"; implying it indicates anything other than breadth of knowledge is inaccurate.
However, since it is useful, here are some resources to begin learning about what intelligence and cognitive research have to say about the matter:
http://www.amazon.com/The-Talent-Code-Greatness-Grown/dp/055...
http://www.amazon.com/The-Genius-All-Us-Insights/dp/03073873...
http://healthland.time.com/2012/12/26/motivation-not-iq-matt...
http://www.cogmed.com/impact-working-memory-training-young-p...
http://www.cogmed.com/working-memory-but-not-iq-predicts-sub...
http://www.cogmed.com/working-memory-training-generalize-imp...
http://www.owlnet.rice.edu/~antonvillado/courses/09a_psyc630...
http://reports-archive.adm.cs.cmu.edu/anon/ml2009/CMU-ML-09-...
http://jabba.edb.utexas.edu/it/enhancingCognitiveSkill.pdf
There are plenty more resources out there, and I'm sure there are much better ones too. But the implication of all this is that learning is a skill, and that you can learn how to learn better. We may not yet thoroughly understand how generalized learning takes place in the brain, but it does seem to be a function of working memory and motivation, which can be improved. Generalized learning is segmented more finely than how I described it originally, but it still functions the same way (e.g. learning to juggle may not help you learn a new language better, but learning to play a musical instrument may help you to learn the other two more easily, since it incorporates language skills through music, and motor skills through playing). Making an argument against this model would place the burden of proof on that side, because as I mentioned before, there is no known mechanism that would lead to the outcome outlined by the 'fair'/balanced model, and it would have to explain away phenomena like neuroplasticity that seem to directly oppose it.
If a person learned to become exceptionally 'talented' in one area, then he/she's more likely to replicate that same level success in a completely new area
The only limiting factor on skill acquisition is choice/taste.
Doesn't genetics also have some role here? The references you just included do nothing to provide any sort of evidence for those statements. To what extents cognitive skills are transferable is still much debated and science is far from having an unanimous answer. Good overview of the issue is here:
http://www4.ncsu.edu/~jlnietfe/EDP504_Notes_files/Are%20Cogn...
Now, it is certainly much harder for some people to acquire certain skills, and it may be near impossible to excel at them up to a certain level (e.g. physical athleticism). But skill level is again different from the skill itself, and it is the skills themselves that matter in skill acquisition. For example, if running ability is found to be genetically limited, then getting any better at it may be harder for you, but picking up a sport like football would probably still be much easier for you if you trained your running first regardless. IQ being genetically determined can impact other things like motivation; i.e. if you have a low IQ things will be harder for you, making you less likely to pursue skill acquisition in the future, and conversely, a high IQ may predispose you to acquiring more skills since they come so easily to you, but the point is that neither absolutely determine how many skills you can/will acquire.
I made a 'bold' statement because it's just that practical of a perspective to take[2]. And science backs it up not only in terms of all the positive effects exercising brain plasticity brings[3], but also in the fact that IQ isn't an end-all be-all metric. It is significant, and highly correlated to other important things like life expectancy[4], but IQ itself is not the limit. A built-in limit to skill acquisition would have to come somewhere else down the line if there is one. I study this stuff on my free time because it interests me, I'm not an expert/scientist, so trying to discover a well-defined concrete limit to skill acquisition is beyond my domain, but stuff like epigenetics and plasticity is making it harder to believe there is one.
[1] I believe the last cite in my previous comment shows an example of this. Also, I myself have a pretty average IQ of ~114 or something, but this view has allowed me to learn a surprising number of skills before I even knew any of the science around it, so of course I'm biased and wanted to share.
[2] Well, that and the fact that most people simply don't bother to look at painfully constructed source lists anyway, making the endeavor of compiling them less worth it.
[3] One example: http://news.stanford.edu/news/2003/september24/dementia.html
[4] http://www.mrc.ac.uk/About/AnnualReview09-10/SevenAges/Elder...
I think you are falling for this in certain places as well, for example when talking about genetic skill level limitations you jump right to physical athleticism, which is something people are somehow able to accept more easily, while there is strong evidence that intellectual abilities are open to limitations of the same kind.
IQ is an imperfect measure that is at best correlated with the "quality" of ones genetic endowment, but it doesn't mean that the genetic limitations are any less real. This is the very old and heated debate of "nature vs. nurture", and I would appreciate your comment much more if you also included views of the "opposing" side and moderated your claims to what the research really says, while I think you are making some big extrapolations. That is not to deny the possibility of "learning to learn" or to discourage learning, but you used very strong phrases.
The system is much too complex to assume that just because we don't have what amounts to total 'free' will that we're hopeless to improve anything at our level of operation. If someone's determined (pun intended) to be a defeatist, then alright, but some others are just waiting for the right inputs to take them down a more useful branch of execution. Because just like a program, even though everything is neatly outlined and determined, that doesn't mean you know what every output ever will be. That's why I don't think 'hardcore' determinism to the point of discouraging choices is a useful view to take, much like how hardcore philosophical skepticism is a dead-end line of logic; neither really provide anything you can build off of, so while they may ultimately be true, they're poor models for productivity. I mean, it's possible that you're right and I'm just having a hard case of cognitive dissonance, but it seems to me like extrapolating deterministic genetic algorithms to argue against useful high-level perspectives is still making a lot of assumptions about the implications of such a system. Meanwhile, I'm just reporting observations that been found with regards to skill acquisition.
[1] The phenomenon depicted on this episode of Radiolab with regards to Transient Global Amnesia is particularly damning (http://www.radiolab.org/2011/oct/04/ ), because it shows that when given all the same inputs, you're likely to perform the exact same actions over-and-over again. The separated twin studies on IQ also show a remarkable number of personality similarities amongst twins (besides IQ), which indicates a possible genetic component to random things like sense of humor. There's no hard evidence that any of these things are genetically determined of course, but meh. Let's also not forget that epigenetics and GMOs exist, though it may be a while before that becomes useful for GATTACA-like situations, lol.
[2] Yes, genetics and other deterministic factors count as inputs. If you want to reach a branch of logic that requires AND-ing with a genetic component you don't have, then tough luck, but a simple OR with some other less deterministic input is equally possible. Of course, this is just another hypothetical model to cope with our lack of understanding.
Greeks celebrated such great thinkers. Leonardo da Vinci, Michelangelo, Galileo Galilei, Nicolaus Copernicus, Francis Bacon and Michael Servetus were all amazing polymaths. - They had expertise in Math, Engineering, Philosophy, Art, Finance. (Perhaps not marketing because such a thing didn't exist back then.)
There have been such multi disciplinary experts in the world and I'm sure there continue to be. But they are rare and often found pursuing interest in one of the areas.
If you can understand tech there is no reason you cannot understand sales and vice versa. - In fact being blind to an alternative point of view isn't even a feature of a man of class. And if you can understand it, why can't you think the same way.
There would be no Apple.
FWIW, they really did appreciate each other. I'm not sure what could have made things work out better - but note that Jobs left too (i.e. kicked out). It's turbulent waters, hard to plan.
fun fact when the iPhone 4S was publicised as having "dual-core graphics", Woz complained that this technical detail was not relevant to users, only the result was. He appreciates Jobs' perspective better than present-day Apple does.