A lot of people aren't going to be willing or able to actually engage with the real logic of an anti-racist argument. Instead, people use heuristics for this sort of work. In my ideal world, the question of "was this on a big site? or some little blog and/or known racist publication?" would serve as a useful heuristic re: what arguments to bother with. This is how newspapers generally settled out. Is it in the paper? If yes, then there are at least some standards. If no, e.g. if it's some vanity publication, then squint a little harder.
These sorts of things have happened every time we've had a big shift in information distribution technology. There's an explosion of ideas with no real markers to differentiate them, and mass chaos for a while as people sort it out. Then eventually people identify the signs of trustworthy info distributors, and it settles back down. If a platform allows racists to flourish, they're not going to remain a place that people can trust. I would like to see Reddit remain a place that has some amount of trust, so I'm happy they banned the really nasty racists.