I wouldn't consider Santa Cruz to be part of SV and definitely not Davis. There are plenty of significant educational institutions in the Bay Area and even more if you expand the net to Northern California, but SV's prominence is driven more by the location there of early tech companies than any educational drivers outside of Stanford (although Stanford is very important).
I disagree, I think education is one of the foundational pieces of what created SV and helps maintain is tech ecosystem. There was something that got those early tech companies to be here in the first place and I don't think it was just luck.
My opinion is that there are 3 main drivers and that top tier education is one of the most important ones.
They go like this:
Higher education that has enough gravity to aggregates diverse 'cutting edge' people from a variety of pursuits.
A reason for those smart people to stay that isn't just money. I think that's lifestyle and access to nature. You have the ocean, mountains, wine country, and relatively good weather.
The last is capital, I think saying companies is putting the cart before the horse. When I say capital I don't just mean startup capital. The ecosystem has to also have liquidity. There are lots of areas that have one of the 3, but very few that have all of them.
