It’s fair to say at this point that Steam is an enormous part of the PC gaming market. It’s also fair to say that Valve has demonstrated very little interest in moderating the platform in any way, preferring algorithms to actually walking in and stopping review-bombing efforts (among other abuses). There’s no real way to program in algorithms to prevent hate groups forming, but it does appear that Valve has gone through the Steam Groups and done one of its most aggressive banning passes to shut down hate groups.
Successful? Well, you won’t find a bunch of hate groups by searching for “school shooter.” You can, however, still find them; you just have to work a little bit harder at it. At this point, it seems that the only way these groups are really going to be removed from the platform altogether is if Valve really makes an aggressive project of moderating the platform, and that seems unlikely. But it’s a step in the right direction.