Even if people had control of perfect opt in filtering that meant you'd never see somebody talking about subhuman n*ggers unless you deliberately choose to, it is in society's best interests to limit the spread of that message and reinforcement of behavior that inevitably leads to harm to the object of their hatred. That hatred might manifest as street altercations, murder, or verbal assault. Being able to see that there are millions of other racists subscribed to r/whitepower encourages racists to feel like it's normal and just another point of view. I mean like, sure that's pretty much what r/tuckercarlson is, but they have to speak in coffee at least.
See my prior post regarding how insulting, and frankly sad, it is to see so many people being fully bought into the idea of there being tens of millions of "racists in waiting" just waiting for their chance to connect with a Racist group online where they'll instantly transform from a 3 of out 10 on the racism scale to 11 out of 10 overnight(or over 20 years) because of that.
You ever consider the possibility that also works in reverse? That 3/10 guy, once exposed to 10/10 guy might
very quickly become 1/10 guy instead. That is kind of what happened in the 1960's when the racism of the deep south was given national news coverage on television. Why should you expect people would find "full exposure" any less repugnant today?
Sure, if you let the racists "groom" their targets, you leave those people wide open for conversion, a little bit at a time. But they can only do that now because in major media channels, all they could hope to encounter is a
caricature of such groups on a television drama or action/adventure.