Think about all the big companies you know.
None of them - except banks/insurance are really in the city.
Look at Twitter, they almost got there, now dwindling.
I've worked at a few startups, and visited a zillion.
Though Goog/FB do have a cool/trendy vibe ... I can't help but feel that most of them wouldn't fit city life very well.
I knew some Engs. in the Valley - super smart dudes who never heard of ISIS. I mean, man. They don't even watch the news. Work -> kids -> geeky projects -> riding. That's it. I don't blame them at all ... But I really do think that the culture out in the burbs is more amenable to 'Empire Building' and getting loyal, normal, predictable folks.
BTW - banks have a lot of job hoppers - because their career paths are so formalized, it's not a big deal for people to hope from one building to the next. Some of the systems are identical, if not entirely the cultures. And many forms of banking are intensely social, which is not like tech.
I also think most banking types tend to be 'upper urban' type people - or at least aspire to that. Tech people are more low key about things.
Anyhow, just my observation.
Less than 50 people work in a typical datacenters. All the R&D to make the datacenter is done outside of it, in R&D centers.
Amazon is one example.