>I'd rather judge for myself a comment's worth than have it faded out for me.
It's not for you, it's a feedback for the commenter. And making your comment unpleasant for others adds an emotional component into the feedback, which is quite effective.
But it also affects "me" and anyone who tries to follow a discussion by making the text harder to read. The commenter already has a feedback on the visible-to-them score. Why not make negative scores visible to everyone instead (even make the score red or whatever to point out this is a negative comment)? After all at the moment you introduce this visual change you do not care about the bandwagoning aspect anymore.
It's not for you, it's a feedback for the commenter. And making your comment unpleasant for others adds an emotional component into the feedback, which is quite effective.