I spent almost a decade at Amazon. Their system for removing low performers has two key flaws.
First, the mandatory minimums. If an org is full of superstars, the org still has to ensure it has at least X% turnover per year, so a superstar has to go. Usually well-performing devs whose manager wasn't skilled enough to convince the larger group that all of their people are superstars.
It's cruel, unfair, and harms the company far more than it has ever helped them.
The second problem is that sociopaths can and do abuse it. There isn't supposed to be a way for a manager to fire someone on a PIP when they ask for a transfer. There's also at least one manager in the Toronto office who openly brags that he does it. He's been there a long time, and the devs warn each other not to go work for that guy if you value your job.
Being a sociopath is not a requirement to become a senior leader at Amazon, but the qualities of a sociopath strongly overlap with the qualities it takes to get those promotions. So naturally, the systems in place are designed to favour sociopath behaviours. There is no system to try to identify and remove such people who abuse the PIP system, because the people in charge would never want such a system.
Kind of glad I left. When I chose which offer to take, I decided to turn down a much higher paying offer because "That company feels too much like Amazon".