I would very much like a world where upvotes and downvotes are not symmetric. As is we say total is upvotes minus downvotes, but in reality upvotes exist to say "good job" and downvotes should exist to say "this is spam or unnecessary"

A better system, IMO, would be to make downvoting closer to reporting, a little harder to do, but if the ratio of down to up passes a certain threshold, the comment is then flagged for review and/or just massively downgraded.

Oh, and you cannot do that to something you reply to. Either say "this is trash not worth engaging with" and move on, thus ensuring trolls do not get fed, or reply but acknowledge it was worth engagement.