I'm answering late, and at least one other person gave the answer, which is Voyager.

The tagging is great because you can make a note about user (positive or negative) and you'll see that come up in any comment they make.

For instance, I can tag a user with a red "Avoid - Troll" and I'll be warned about their propensity to say inflammatory stuff without having to block them altogether.

The trouble with blocking is that you sometimes miss valuable comments that are replies.