I think this thread is one of those with an obvious answer. Yes, top schools are full of top students. And the fact that they are obviously translates to teaching to their students’ abilities.
But, it is equally true that lots of top-talented kids cannot afford to attend top schools. Finances are a filter, regardless of ability. Those students are found on campuses everywhere. They stratify on campuses by major/organizations/specialized programs, etc.
My kids have only attend non-selective colleges and I think amg them, the total number of MC tests can be counted on one hand. (4 universities in 3 different states.) They have had seminar classes, essays with thorough critiquing, and classes where the textbook is only a portion of the total course content. And, yes, classes which demand high levels of critical thinking (I am trying to picture sr level chemE classes or physics classes which are educational jell-o. 
) Different than at a highly selective school? Yes. Academically deficient? No, not if work experience validates educational background.
If you look though the list of Goldwater Scholars (just one award I happen to be familiar with), yes, students from top schools abound. You also see students from flagships. But, then you also see students from directional/regional schools. https://goldwater.scholarsapply.org/sch-2015.php Those students didn’t receive those awards for sitting in a classroom regurgitating their textbook on MC tests. Professors took interest in those students and worked with them.
Maybe a better question rather than one with an obvious yes for the answer is “are the elites the only path to a highly challenging and successful educational outcome?”