I'm still trying to understand why Mumbles needs to be banned if blocking him will accomplish the same thing, for those who hate him.

Blocking is only ineffective when:

1) The user constantly trolls you, and will simply talk shit behind your back if you block him
-or-
2) The user is at the center of a lot of conversations and is getting tons of responses to his messages

From what I've seen, Mumbles rarely trolls people, and most responses to him tend to be things like "stfu, you're terrible" or "stop googling things to appear smart".

So if all the Mumbles-haters block him, there will be few responses to his messages, nor would there be a lot of back-and-forth conversations with him which they'd be partially missing.

That's what I suggest if you can't stand seeing his posts.