One thing about fat that I think is overlooked is how fat today might be muscle tomorrow, and how little companies try to convert it.
Maybe a person is in a bad role, on a bad team, or simply doesn't have experience or skills fitting the specific requirements of that single point in time. I've been a high performer in the past. Now I'm a low performer (I'm slow) after the company has changed the way it treats teams/work and the technology shifted. My disability isn't suited to the new working style/process (or lack of). However, I do excellent work outside of my regular day to day responsibilities, like my secondary role as an ASC. My manager even said that I'd I could just speed up my regular work I would easily get the highest rating and a promotion. Hearing him say that really sucks because I unable to just speed up with my disability in the given work environment. The company/managers have made no effort in helping me find a role that works better with my skills or is impacted less by my disability. It seems there may not be any of the traditional roles/teams left. So now I fill midlevel roles and move team to team trying to find somewhere that I fit in. If I can find a place I fit in like before, then I would easily excel.
Another example was a dev on another team that I worked with a few years ago was sloppy, slow, and just all around seemed like a poor performer - and even our tech lead and manager talked poorly about him. He was even considerably slower than me. About 3 years after that he's now the head of data and analytics for our international operations.
One underlying problem with these PIP type programs at FAANG seems to be that they have very high barriers to entry in the interview process, and then act like 30% of the company is underperforming and subject to an annual 6% cull.
There are industries & companies that have grown fat & lazy and could use a few annual 6% culls, but you eventually run out of fat. If you have a very competitive interview process and high compensation to attract the best talent, it is unlikely you have so many underperformers lying about to cull annually.
So really it's overhiring BS that is then getting taken out on employees. Given that, I think as has been pointed out by another commenter - the old Wall St model of doing one cut in one afternoon, calling people into an office and giving a severance is far more humane. Everyone understood it was about the numbers not about your performance, generally. Seems better than year round psychological torture of being at risk of a PIP, and then if being put on one knowing the most likely outcome is being fired. So you feel dragged through the mud and then having doubly failed (put on PIP & failed the PIP).
I knew a guy who moved from Wall St to Amazon and described the performance management / compensation system to be pretty rough and had explicitly described the compensation cliff and how a lot of people in the good years were proactively leaving, cooling off, and then coming back to reset the compensation instead of going over the cliff.