This does not mean to say that most, or even very many, people working at Facebook are as morally challenged as Zuckerberg seems to me to be. But the fact that I think that some of Facebook's controversial decisions come from Zuckerberg, and that I don't think Zuckerberg is acting in good faith, is why I view various incidents involving Facebook as being more evil.
As for the valley being small, it is but I don't live there. And it seems unlikely that I will ever live there. Furthermore my feelings about any particular company don't generally extend to the rank and file working there. Similarly I don't let my hatred of Microsoft's policies get in the way of my having friendships with people who work at, or used to work at, Microsoft.