A certain Y Combinator startup (two-sided labor marketplace in healthcare and nursing homes) requires that its frontline managers PIP or fire at least half of their team each year and sometimes more frequently. "If you're average, why are you here."

And the managers do because they are terrified about losing their jobs. It has one of the worst cultures, and code bases, in the world, because nobody knows how things work or why decisions got made, and no one trusts their team mates enough to ask questions.

Its all done in the name of excellence.