Obviously that’s true, but the discussion isn’t around a cohort, it’s about 1 person. There is a lot of research out there that supports the edge provided by a more selective undergrad experience for admission to graduate and medical schools.
The same kid with the same grades and the same MCAT scores will have a better chance of acceptance with Bryn Mawr on their resume than the other schools mentioned.
The experience of college is important, and nobody should ever go someplace just for prestige…but there is value is reputation. If there wasn’t, CC wouldn’t be so busy with discussions focused on 5% of all colleges in the US.