I saw an explanation later in this thread that made more sense. FANGs do have a lot of good employees. And if they didn’t pay high salaries other companies would simply swoop in and free ride on all the hard work they do to find and groom talent. FANGs spend a lot of money scouring the entire globe and interviewing so many people in detail. It’s a juicy target for recruiter raiding. And just like you can’t get fired for hiring IBM you can’t get fired for hiring FANG. This attracts yet more talent. But yes the level of the engineers is not as great as the salaries would suggest.
But on the flip side for anyone doing hiring. If you want some wicked smart devs who don’t ask for as much then look at game devs.