If HYPSM reject, say, 65% of students w/ perfect GPAs and SAT/ACT scores, that means 35% get in. That's good odds, no?

Yes, this is going to be the problem. The published ranges will only be from those who submitted scores. You will certainly get a higher range representing a smaller segment of students.

I would wager that if you took the top 40-50% of the scores of admitted students pre-TO and compare them to the published range when TO CDSs are published in a few months, they wouldn’t be meaningfully different.

But we can’t do that. We will end up with NYU going from showing a 1450 25-75% midpoint on their 20-21 CDS to, based on a press release, around a 1540 on the 21-22.

Also…

If HPYSM reject, say, 95% of students w/perfect GPA and SAT/ACT scores, that means 5% get in. That’s not much better odds, is it?

If we just “say” a number, it can be anything. I’m not clear on the meaning of this hypothetical.