It's just cheaper. That's the most important thing for corporations. It's also harder to accuse them of bias. Personally, I'm a little dubious about the effectiveness of fact checkers on people's opinions. If someone is a dullard who is willing to believe the most absurd propaganda or every conspiracy theory that exists, a fact checker won't solve the problem. They are used to being told that they are wrong. Of course they just can shadowban this content but in the end they profit from that.