At least in my friend group (mostly White, Asian, and Latiné who attended the Top 50 ranked US News schools), most of us already knew each other via competitive high school extracurriculars (eg. Debate, Sports, DECA, MUN, Science Olympiads, Quiz Bowl, SAT Bootcamp, Intel Science Fair, Cyberpatriot, etc) and because we all attended the same 200-300 high schools nationally, did the same 5-7 majors, and are working in the same 3-4 industries.
Flagship Public Schools are becoming elite as well now that they are becoming much more selective, as well as the fact that STEM is increasingly valued outside the STEM industry (eg. PE/IB loves hire CS and Applied Math grads from target schools due to their analytical background)
Y'all boomers are arguing over a tree while ignoring the forest.