Trying to engage with your point with a straight face: I strongly oppose this because I personally experienced both public schools and a selective university,

Trying to engage with your point with a straight face: I strongly oppose this because I personally experienced both public schools and a selective university, and I strongly doubt that it's possible to retain most of the good elements of my university experience without some amount of a selective admission process. The idea that a randomly selected set of the population can produce the same academic and social value that you get from a selected set of people who passed an admissions bar is hopelessly naive, in my experience. Even the much-derided effect that prestigious schools serve merely to "label" people who pass the admissions bar has worked out well for me. As someone who has both the intelligence and conscientiousness to work to and through a good university, it's nice to have a document and label certifying that fact, and I legitimately think the world is in fact better for it. Does university have problems? Sure. Are there people harmed by the existence of the US university system? Probably. But I can testify that my life has been very significantly improved by the existence of university admissions processes, and the honest answer to "what if universities accepted anyone who applied" is that I would personally have tried very hard to find something else (either here or in some other country) that fills the same role. This is a bad idea because it stunts the growth of a lot of people and destroys an institution that has a lot of value, and those things are bad for all the normal reasons.