If people on Twitter say incorrect facts about a group of people, or even start egging people towards violence, there's a lot of pushback against that there.
But if that random person is removed from Twitter and starts seeking out like-minded people, they're going to form some underground community with no pushback against the worst ideas.
1) IMHO, using a phrase like "Nazi propaganda" knowingly poisons the well in these discussions because basically anything just a bit out of the current political zeitgeist can be and has been labeled as Nazi propaganda in CURRENT_YEAR.
2) Since you seem to hate Nazis so much, why are you adopting the digital equivalent of their tactics? The Nazis famously burned lots of very Jewish books, right? Society used to say that this was one of the examples of why they weren't so great, and I grew up hating the idea of burning books because of this. I can't understand how using their playbook suddenly became doubleplusgood.
Feel free to interpret this as "people who have actual swastika flags in their rooms and think that the way to create the best society is to mass murder jewish people."
That's a real population of extremists. Having them hang out on HN does not make their numbers dwindle.
And no, I do not think that banning Nazis from forums is "the same playbook" used by the Nazi Party.
I can't take any claims about "the Nazis" seriously in CURRENT_YEAR because the label is thrown out so casually. I've seen some of the most commonplace and benign beliefs unironically labeled as Nazi to try and get a minor bit of political advantage.