That's live now? Awesome! We've been needing that for... well, years, actually, but it got really bad a couple of months ago. "Troll feeding fee" is such a very apt description, too.

Really? Isn't hiding of down-voted comments enough? It protects people from seeing crap unless they explicitly ask for it (and they should be able to). There could still be a problem if comment threads were sprinkled with huge contiguous swathes of hidden comments but does that actually happen? (I think that the maximum number of contiguous hidden comments that I have seen is two.)

I find the fact that even obviously aggressive and stupid stuff tends to be replied to in a polite and informative manner one of impressive things about LessWrong. Some are concerned that this place appears dogmatic to newcomers. Having massive down-voting accompanied by explanations is one way in which those concerns can be alleviated.

Curiously, I initially wanted to downvote your comment but hesitated because I didn't want people replying to it being punished. On reflection, your comment might not actually merit downvoting (I think there was a bit of 'who the hell he thinks he is, treating LessWrong as his own private playground' knee-jerk reaction here), but this is not at all a good sign on what effects this will have on troll-fighting. There are comments that are stupid but seem to be made in good faith and thus be worthy of a response. If I don't feel like making that response, I might just downvote and be on my way. Now, downvoting will provide a disincentive to any potential educators which in turn discourages downvoting itself.

And finally, people who strongly dislike that change can decide to mentally subtract 5 points of karma from the score of each reply to a comment that's at -3 or below and then base their voting decision on that (which will tend to push the scores of such replies to 5 + whatever they would have gotten otherwise), so nyah!