It's weird to me to see that stuff in Twitter screenshots. Because, Twitter seems so public to me. Don't they risk getting banned immediately just saying things

It's weird to me to see that stuff in Twitter screenshots. Because, Twitter seems so public to me. Don't they risk getting banned immediately just saying things like that? Or does Twitter only really police people who harass celebrities? 4chan.. I mean, it seems like the only reason 4chan would still be allowed to exist is to make it easier for the FBI etc. to monitor the kind of garbage that goes on in 4chan in one place.