Most employers don't allow drinking at work. Some allow it at company events, provided it doesn't become a problem. The funny thing is about a lot of Silicon Valley companies, I think, is that they decided in their attempt to reinvent work that they'd throw out a couple hundred years of learned experience on what does and doesn't work in a corporate setting.

The "fun places to work" eventually figure out that fun for some is often at the expense of others, and that most things corporate environments have ruled out were ruled out a long time ago because they didn't work well.