If we can look globally, even within 50 years, Marxists (e.g., Khmer Rouge, and Mao's Cultural Revolution) have killed many orders of magnitude more people than have racial separatists or supremacists.
If we look back further, you at least pick up the Nazis on the racial supremacist side, but that still doesn't get you within an order of magnitude of Mao, Stalin, and friends.
Within the USA, the Constitution has protected us, but we can still see pernicious effects of Marxism. It's harder to quantify this, but I don't think there's a clear case that either side is "winning".
Again, I am not a fan of hard core authoritarian Marxism and would be concerned if these people had real power or larger numbers and serious funding. I was simply pointing out that as of today they are few, lack funding or serious organization, and seem to advocate and enact violence much less often than the extreme right. They can be just as trollish though, I'll give them that.
BTW /r/ChapoTrapHouse was also banned for advocacy of violence and trolling/brigading.
I am not a fan of revolutionary Marxism, but in terms of actual danger to people I don't see them as nearly as much of a risk. They also have far less funding than the extreme right and seem to be far fewer in number.
If revolutionary Marxists start killing people or conducting acts of domestic terror, then yes ban those people. Let me know next time a revolutionary Marxist shoots up a school.