I would disagree with the idea that a degree from certain universities is particularly required, or that Silicon Valley somehow looks past people’s educational record. Steve Wozniak and people like that are rare exceptions.
Some university degrees are more prestigious than others, certainly, and there has been the phenomenon in the UK in recent years of polytechnics suddenly declaring themselves to be “universities”, which has perhaps devalued the idea of a university degree, but having the letters BA or BSc still matters in the job market, and not just if it is an “Oxbridge” degree. I don’t see how that is different from the situation in the US.