Earlier quoted context omitted.
> So a manager might make a bad hire because so they don't have to fire any of the people they like. This is well documented behavior, even in Jack Welch’s book. He was the one famous for cutting 5% every year at GE.
At Amazon*, the "bar raiser" has to approve the hire though, so there's a pretty mechanistic control against the worst form of this. * - as I understand it; never worked there.
You can still have bad hires. It happens rarely that the bar raising process outright fails, but it still happens, since the data you get out of an interview is very limited. For example, we had a team member that not only was doing a bad job on his own stuff, he was a drain on morale and resources for the whole team, since he constantly complained about everything, he never tried to learn anything, he posted big commit dumps every few months - hundreds of commits at once - and the code quality on those was abysmal. Luckily we got rid of him pretty fast, but not fast enough.