The original post was about Google and generally I’d say FB is indeed faster to hire and also faster to pip/fire than Google. Compared to Amazon and Netflix, probably not.
I was a manager at FB for a couple of years. Basically, my first official act as a manager was firing someone. From there, it was pretty much, "find one person on your team per year to fire."
It was an extremely high performing team, and even the less talented engineers were still very good.