I've seen other companies with a variety of weirdly dysfunctional ways of treating employees, but what's the Tolstoy quote? "Happy families are all alike; every unhappy family is unhappy in its own way." If you have a decent network in Silicon Valley, and/or are willing/able to bounce once a situation seems bad, it's pretty easy to stay in "Happy families" only.
I don't think Silicon Valley vs. New York has a lot to do with it.
The problem is that when you run into bad people and they ruin your career or steal your future, then good people don't want anything to do with you (or, at least, have you at arms' length, and that gets annoying) so you get a string of more bad people (who are always happy to take advantage of your weakened position).
You basically have to play degenerate political games to get investor contact as an employee of a funded startup. It really is a two-class world these days.
My experience is based on what I've seen in New York, but everything I've heard about the Valley is that it's the same. Well-connected douches will always have a competitive advantage over real people. We get our shot when tech becomes uncool/nerdy again and those assholes go back to whatever douche Valhalla they return to.