> These sub-communities that people want to censor, do they have any redeeming value?
The usual example would be cartoon child pornography. Some want to see it wiped off the face of earth, others argue it provides an outlet for pedophiles.
> Or are you just making a slippery-slope argument that this might be a precedent for some hypothetical future censorship of something worthwhile?
Maybe that too, but it's more about that they are not illegal, which means the judicial system has not found that they shouldn't exist and no attempt has been made to bring about such a decision. If its not the judicial system, who should be the arbiter of communities that are allowed to exist? Do we want facebook, google and cloudflare to be community-shepherds?