Neonazis, communists, would be anarchists, followers of 1000 cults and political groups many mutually offensive to one another can all be heard at least by millions of like minded individuals even if the rest of society isn't interested. You can even maintain a presence on public social media while advocating for evil and crime so long as you maintain a public face where you keep within bounds and talk about the obvious illegality in private.
It is the lack of societal suppression indeed that is so disturbing to conservatives that they agitate for the large scale restructuring of society to restore the "proper order" greatly to the disadvantage of many.
Their speech is dangerous. It's not a given that they will be defeated. Establishing some standards on platforms to deny them a mass audience while still keeping the wide open internet free for anyone to use seems virtuous.
I don’t get how it is any different from the anticommunist fervor you are decrying. Your stand is basically to let various crazy people to have crazy ideas unless there become too many of them and they would be deemed a threat at which point they should be censored and discriminated.
> Protection, therefore, against the tyranny of the magistrate is not enough: there needs protection also against the tyranny of the prevailing opinion and feeling; against the tendency of society to impose, by other means than civil penalties, its own ideas and practices as rules of conduct on those who dissent from them; to fetter the development, and, if possible, prevent the formation, of any individuality not in harmony with its ways, and compel all characters to fashion themselves upon the model of its own. There is a limit to the legitimate interference of collective opinion with individual independence: and to find that limit, and maintain it against encroachment, is as indispensable to a good condition of human affairs, as protection against political despotism.
~ John Stuart Mill, On Liberty