After graduating from a bog standard state school, it took me 20 years of job hopping from one non-name-brand company to another before I finally got into a FAANG company. And once you're inside, you can see why this is: You're surrounded by a monoculture of Stanford and MIT and Berkeley graduates, because those (and a few others) are where they do all their university recruitment. Not to pick on graduates of those great schools in particular. They're generally smart folks. It's just that big tech seems to focus on a small number of schools and practically ignore all the other ones.