Damages for defamation are hard to prove.
If someone with a million followers says on Twitter, "I don't like Bob", then Bob is never going to get hired anywhere, but there's no legal case. Indeed, the person voicing the opinion didn't break any laws or do anything wrong--the problem, rather, is with employers who refuse to hire anyone remotely controversial (and who, in doing so, implement "cancel culture", although it's always been the left that is most viciously cancelled).
Free speech is important, but we need to regulate the shit out of search engines and employers in order to protect people from unearned reputation damage.