You’re not changing anything. You’re literally making things worse by banning them.
I think this is the misunderstaning here. There is no “changing anything”. This is not the purpose of the exercise. The purpose of keeping certain views out of public discourse, is to limit their exposure, in the same way that quarantine limits exposure to infection.
You can have a Nazi who sneezes his ideas into the minds of everyone on national television. That will infect a lot of people. Or you can have a Nazi who has no outlet, but meeting in a basement with his 5 friends, talking about Nazi things among themselves. Those are two extremes. Which is better? What situation should we aspire to?
Of course we are not banishing Nazis from existence. But we are banishing Nazis from looking very cool on national television. If you let them, they will try to do that. Should we let them? What is the benefit in letting them do that?