All that means is this: when you have a larger, more diverse, population base, specialization can be afforded. My corporate office has an employee dedicated to shipping and receiving FedEx packages. But the underlying structure can support that, because we have many analysts, etc.
Being a specialist is just different than a generalist. Do what fits you best. I know I like dabbling in a lot of different things (was a double major, English and CS, in college), so being a generalist works to my strengths. However, I know people who only like their narrow view, but like to know how deep the rabbit hole goes.
Also, some fields require specialization. Working crypto implementations? You'd better be damned specialized. But starting a company requires so many different types of work, that you pretty much have to be a generalist to succeed (or else have 15 people as co-founders who can immediately specialize).
One other thing -- even when there is a group of specialists, you need generalists to bring them together. All things being equal, I would probably prefer a team of generalists for a cofounding team (say, 2-3 people) versus a team of specialists.