I would bet most of the employees they want aren’t the ones they let go, but probably a lot more who went somewhere else of their own volition.
Lots of good employees leave because even with a great boss, if your boss isn’t getting promoted, you might not have a path for promotion without lateraling into something you don’t like, with new people and new relationships who might be worse.
If you’re going to do all that, you might just do it in a new company.
It’s always easier for companies to richly reward new hires vs existing employees.