I think some sites have a feature, that when you downvote, you have to add some words/tags to why you downvote. I like that idea, it gives the commenter some concrete feedback, but also the downvoter a moment for reflection (is this really a bad comment, or do I just have a bite reflex because its language sounds like a (ideological) side I hate?)
I know that I have stupidly taken some downvotes personally, but later realized, those comments were maybe not bad by itself, but in that context attracting flamewar OT debates.
With some extra words, I would have realized sooner.
And downvoting for merely not liking someones opinion is something I really don't like, but is explicitely allowed here.