That report is nonsense. For one thing, hiring takes a lot of work. No manager is going to invest the time in hiring someone just to have an expendable on the team to sacrifice. No manager is going to accept the drag on the team that arises by having a below-standards person on the team. Everyone here is clear that we'd rather do without than have a low-performing co-worker. Finally, even if some misguided manager did want to do this, each Amazon hiring loop has an independent person to enforce the policy that each new hire be better than half the people in a similar role.

It's true that some people leave, and sometimes you're not sorry to see them go. This is true in every line of work.