FWIW, my experience of Google's hiring process wasn't like that at all. Sure, it was hard, and they did do whiteboarding problems in the interviews (all seven of them), which is in its own way terrible, but it was all done with people who really did know the stuff they were asking me about.

I didn't get the job, but it was an interesting experience. Certainly selects for a certain kind of engineer, and would not be my preference for how to hire people if I was setting up my own operation.