> There is a generic flaw in humanity that controversy brings popularity.

Not necessarily. You need to have that controversy shown to enough people of similar mindsets, which requires a platform, or for them to somehow grow their local audience, which was difficult for folks on the fringe to do in the past, but is easy now that social media promotes the fringe.

> So all you have to do is achieve perfect balance and censor only the bad things from both sides, right?

No. Regulate social media that drives views to these people. They're able to exist because social media uses algorithms based on engagement, and these people game the engagement system to slowly radicalize them. If you remove the pipeline, you also lower the popularity of these people.

Sure, some of this is word of mouth, but it's mostly not. Social media actively encouraging people to view this content.

> Because it's better to let every idiot flap their trap than to let anyone else decide who can't.

Yes, but free speech doesn't include the right to be platformed. Depending on the country, the definition of free speech also differs, and I have a feeling you're only considering this from the US point of view.