On version 0.19 you can block instances so that you don’t see any posts from that instance, instead of having to block communities one by one, you still see comments from users of that instance in other posts so it isn’t completely blocking the instance.
I don’t have plans to block any. I’ve already blocked the active communities in some of the instances I might consider blocking in whole to the point I never see posts from those instances anyway as well as any individual problem user I run across. I don’t really see a reason to block an entire server because even the worst places have some good people, just like all the best places still have some shitty people. Unless the instance itself was dedicated to CP or something.