I think you also have to determine the purpose of a university.
It's either to take the top students, bar none, or it is to educate and uplift poorer students (economically and educationally). Mixing these two doesn't work.
It's either to take the top students, bar none, or it is to educate and uplift poorer students (economically and educationally). Mixing these two doesn't work.
Alas, university doesn't work that way: students continue to be measured throughout their tenure, and those measures are an important component of the next phase of their life, be it work or further education.
The evidence is unequivocal: lowering the admissions standards for some section of the student body, results in those students doing poorly relative to students who were subject to the full standards.
This shouldn't be surprising, and no, it doesn't seem to matter why the standards were lowered, affirmative action, legacy preference, or otherwise.
That is in fact exactly how admissions at the UC schools work. The first 1/2 of the class is admitted on test scores and grades alone, the second 1/2 is admitted via reading of their essays and considering other factors, such as extracurriculars, economic circumstance, and, until the 90s, race.
The very definition of what a "top student" is varies a great deal.