It's kinda logical. Most people, individually, have a somewhat unique writing style. So if there's one set of writing that's very formulaic and consistent and you build an averaging machine it's going to converge on that formulaic style because everyone else's writing style is going to be much closer to n=1.

I'd expect that most corporate speak made it past their data curation, while normal people speaking normally was probably scrutinized a bit more heavily. The PC stuff is also probably quite terrified of a lot of adjectives. For instance I just used normal as an adjective, and that can be a hyper-loaded term if somebody's obsessed with trying to interpret things in the most absurdly bad faith way imaginable. By contrast corporate speak tends to have obnoxious lingo, but lingo that can't really be spun too much. Even for one of those guys, mental gymnasticing 'snappy' into being a secret dog whistle's going to be pretty hard.