I feel like a lot of fandom (especially now as opposed to 15 years ago?) is fairly decentralized even if it is a community. Like, you can block someone from commenting on your dreamwidth and reading your Tumblr if they're being offensive, but you can't prevent them from reading your fic on Ao3 if they still want to, or from posting their own.

There's also the question of behavior versus mindset: if someone does something offensive, there are going to be negative consequences. But what if they're behaving politely but have "the wrong" beliefs? Maybe I'm being cynical but some of the rhetoric I've seen feels like it's also directed at those people.