It’s a massive company, with more than 75k employees. At that scale you have to have a lot of dumb people

and, like, literally you need some dumb or mediocre people.

you don't need 75k generals or fighter pilots, you need average folks who are going to STFU and get the unfun, unsexy tasks done.

you go trying to hire a Stanford/MIT hot-shot rockstar type and they'll either crash out or jump ASAP once they realize they got nailed with drudgery.

The employees at any particular company are a random sample of the population, and will therefore have traits that occur in the larger population.

To be fair, you'd have to be pretty dumb to apply to work at Meta anyway.