To create useful content, you don't need to know Google internals.
Full disclosure - I work in SEO.
Note that I am not saying that you yourself perform any of this in your role. Our anger is not at site tuning and placement but the techniques used to do so, which you appear to be unnecessarily defending as essential for any site's survival.
You're automatically assuming that SEO is bad, or is all blackhat, or is just about promoting crap. I would argue vehemently that good SEOs only want to promote good content. I turn down many freelance gigs because the company is shit.
I think you're confusing legitimate SEO with crap affiliate marketing. Big difference there, buddy.
On a high level good sites don't benefit from SEO, because it wastes time and money on something that should be granted: good sites should be ranked high, crap sites should be ranked low. SEO is a cargo cult (http://en.wikipedia.org/wiki/Cargo_cult_science) with no benefits to society.
I think I'd mirror others' analogies. It's more that the complaint is futile - and kind of sad. One comes away with the impression that the author is naive enough about the nature of his profession to genuinely believe that, on this subject, he and Google should be buddies and not adversaries.
Wouldn't it then be harder to demonstrate objective returns if Google's algorithms are so obfuscated? If they're not afraid to game Google for their customer's benefit, they're certainly not going to be afraid to game customer expectations and fudge their results for a living.