Personally, I almost never downvote (unless the user is literally writing one liner responses, insulting, or spamming).

The comments that are grey because they said something controversial are the ones I upvote the most.

I mean if we keep downvoting all the comments we disagree with because of an emotional response to it, how will we ever have an interesting discussion?

Also, I've noticed a pattern that after the depth of let's say 1-2 back and forth, the civility is often lost and the thread is no longer engaging.

One should know when it is a good time to stop replying..