As I noted, there’s no high-minded principle at work here. All these schools are competing with each other to a greater or lesser extent. They all send out marketing materials, although UChicago seems to send out more (in the small sample size that I’m directly familiar with, that’s clearly been the case - maybe because the people in question lined up more closely with something UChicago was looking for).
I also noted - because I agree that a lot of this is about marketing and prestige - that one reason HYPS won’t go ED is that it would send a negative status signal by showing that they felt they needed to do it (and, as you imply, ED is seen as a marker for the next level down). I do believe, though, that the main reason that HYPS don’t fill most of the class ED is that they already have 70-80% yields overall, probably get 80-90+% yields on the roughly half of their classes they admit SCEA and would rather cast the net wider, not send a negative signal to non-full payers by admitting most of the class ED, and take some yield risk in order to get what they view as a better class.
I think you misread me. My point is that if HYPS went test-optional and routinely waived app fees, they’d get thousands more apps than they get now, and they neither want nor need that (with the important qualifier that all these schools are marketing hard for academically elite URMs, since that’s how they burnish their diversity credentials while admitting the academically strongest class).
I don’t know how many kids who apply SCEA need aid and don’t file for it (I hope not many; it seems nuts to me, particularly given that HYPS are need-blind and have an enormous amount of aid available). The point is, though, that a kid who needs aid and applies ED has much less negotiating power than one who applies SCEA, so if UChicago fills most of its classes ED, which seems to be the case, it’s actively deterring those kids. The Empower Initiative is clearly meant to counteract this message, but, as pointed out in this Chicago Maroon article (https://www.chicagomaroon.com/article/2018/6/16/uchicago-get-much-credit-admissions-announcements/), it’s not obvious that financial aid is going to increase much overall.
I don’t think you or I can prove or disprove the first statement, which is why I expressed it as a conjecture. My basis for it was knowing personally some 20 kids who’ve matriculated at UChicago in the past few years. At the places I’m most familiar with (certain non-Midwestern elite prep schools), the kids who go to UChicago tend overwhelmingly to be academically strong but not monastic about it, not recruited athletes, URMs or legacies at any of HYPS or Chicago and infrequently possessing some particular spike. In other words, they tend to be kids who’d fit in fine at HYPS, UChicago or any other top-15 school, and I can’t recall meeting one who thought they only belonged at UChicago (even if they applied ED I/II there, which a number did for strategic reasons). Your mileage will undoubtedly vary, particularly if you live in the Great Lakes area.
Chicago’s undersized endowment relative to its peers is a matter of public record, and has been extensively discussed elsewhere on CC, as has the limited population of super-wealthy alumni of the college. Since financial resources per student and alumni giving rate account for 15% of the US News ranking, my assumption is that the UChicago administration is focused on this too, and going test-optional can help them address it. If UChicago wants to build up that endowment, they’ll need to take a few more development admits (which could certainly include young master Gates, although I know nothing about him and can’t speak to his academic chops one way or another, or why he and UChicago chose each other).
I am tempted to say if it were not so impolite, that this is just “argument from authority”. I didn’t attend UChicago but have spent a fair amount of time studying it, directly and through the prism of alumni I know personally. I’ve got deep, direct experience over decades with some of its peer schools. I’m going to surmise that you, conversely, have about as good a relationship with UChicago as I have with some of its peers, and a weaker relationship with some of those peers than I have. In other words, neither of us can claim to have the full picture on our own.
We can stipulate that all these schools are unique and have distinctive characteristics. As @JHS has often said, though, the top tier are a lot more similar than different, at least in my experience, and I believe that most kids who are happy at one of them could be equally happy at many others. They’re all big and diverse enough, and all have the academic strength to satisfy even the most demanding Chicago kid, even if the overall vibe differs somewhat place to place. With all of the innovations at UChicago tending to make it more closely resemble its peers, I think this will only become more true.