Students at Yale are, for the most part, all strikingly similar – same socioeconomic class, same interests, same pursuits, same life goals, even the same style of dress.

Can I ask on what basis you're drawing this conclusion? I agree with the bulk of what you said about overuse of negative selection, but I challenge the idea that it's producing cookie-cutter student bodies at elite universities. Having attended Yale as an undergrad, your claim strikes me as incorrect, as the Yale student body seemed to me more diverse on all five of those categories than any other (non-online) community I've been a part of -- certainly more so than my high school, my law school, or my current professional environment. That's just my anecdotal experience, so I'm open to the idea that I'm mistaken if you have some more formal analysis to back this up. But this statement jumped out at me as questionable, so I wanted to see where you were getting it from.