Having everything you say attached to your name forever seems extremely icky (we both know that "banned" and "deleted" don't mean anything on the internet). In an hypothetical perfect world with hypothetical perfectly rational people why not, in the mess we live in it would be a nightmare.
I don't know why people feel entitled to say something without facing the consequences of it. If you don't believe in it enough to defend your position and put forward your reputation, you don't need to say it.
Why do you need to deceive people? Let's say, you are a racist and feel very strongly to say something about your opinions. Say it and win the argument and improve your life or say it and lose the argument and people can choose not to be associated with you.
That's a fair situation, what's not fair is to annoy people or maybe even harm them from another persona and then pretend that you are something else.