I do think that the idea of a mute isn't entirely a good thing. I do think it's fine to allow single users to mute single people, but I don't think those people should be prevented from commenting on that person's submissions. Imagine I start muting everyone that disagrees with me. Imagine a tag starts muting all those who disagree with them, it encourages a "echo chamber" effect, or I'd imagine it would.
I mean, what does it hurt if a person can post on something but is invisible to you. If nobody else likes what that person says, they will mute the person also. It seems like an unnecessary restriction to me that only serves to promote abuse. I am talking from the viewpoint of someone who loves to go into said echo-chambers and try to get a dissenting opinion going. Not troll, but actually give good content. Problem is I'd see entire communities muting me for doing something like that, where previously mods would not ban. Then again, I would just be able to make my own posts in order to show those contrary points, but it still seems unnecessary that i'd resort to that rather than just being able to invisibly post in comment threads.