You can do that on email, irl, with real letters, etc. It hasn’t been a problem. If someone is particularly harassing you then it becomes a legal issue.
What Twitter could do is just stop promoting and spreading content people don’t like. Rather than completely ban problem users like trump, just stop showing them in trending feeds and give people the option to block the users so you don’t see them.
Yes - a lot of people claim that shadow banning, downranking etc. are censorship. I disagree, they necessary to keep online places as civil as they are.
There's also content that is regarded by mental health experts as harmful in large quantities - downranking that is also important to not cause existential harm to people.
What Twitter could do is just stop promoting and spreading content people don’t like. Rather than completely ban problem users like trump, just stop showing them in trending feeds and give people the option to block the users so you don’t see them.