To grow a company, you need to be good at killing things

This applies to farming. I learned that, in order to grow a crop, the important thing is not keeping it alive as much as keeping everything else dead. Parasites, competitors, predators. Dead. The idea is to make leave the crop alone in its personal, practically desertic garden of eden with all the water and sun and shade and nutrients it needs.

Killing employees at least is relatively easy, because their cost is obvious.

Killing features and code, while often at least as important, usually turns out to be practically impossible - because so many people will always argue that they "have no cost".