Sorry, don't agree. Forcing them to congregate on unpopular websites is great because those websites have a terrible reputation and that massively hinders recruitment. Sure, they're echo chambers, but extremists already use private fora for more underground organizing activity and likewise there are people who specialize in monitoring and infiltrating those websites.
If your argument is that they just need to be talked around with reason and logic, you can always go to one of their websites and give it a try. Sure, deradicalization can work and it's great when it does, but generally the odds are poor and it's extremely labor intensive.
If they promote violence or brigade, harass, or attack other members directly on FB then. Then yes, they should have their pages shut down. That is more than sufficient rather than saying any language that can be categorized in a very broad and vague category will be banned.
The simple fact alone if you asked various people in America to define a "literal Nazi" you'll get a hundred different answers of who should fit into that category.
And for definitions: I think it’s very clear to indentify fascist thought - favorable views on ethnic cleansing and stories about mighty groups of people that can’t be proven should never be tolerated.
The massive danger is going to be the countless false positives this thinking generates. Just like the craziness of arresting the guy whose dog made a nazi salute in the video.
He would be denied access to social media because of stupid interpretations of a joke.
This isn't about defending or persecuting Nazis, it's about protecting the public from systems of abuse.
Not to mention the ineffectiveness of online censorship. The only worse thing are Nazis organizing on public platforms is forcing them to congregate only with other Nazis on radical websites where no one will challenge their worldview. But that's a totally different discussion.