They have always had their own platforms, using forum software and the like. They will use any free software regular people will use. They always had their own isolated corners of the internet.

So then the question is whether these people would cease to be nazis or pedophiles if only they interacted with “normal” people. Decades of that mindset have gone by and the answer is “no.” They want tu be in normie spaces to convince others, they’re not going to deradicalize like that. Deradicalization is hard, time consuming for volunteers, and rare, as well as rarely complete. And even if it were effective, it is unethical to demand the people they target be the ones to deradicalize them. Nobody here signed an agreement to be a nazi pedo’s unpaid therapist.