I think voting based on quality of content (and NOT whether you agree with it) is the best approach for healthy discussions. If somebody is a low effort troll, then for sure downvote (and maybe even consider reporting).
OTOH, if somebody makes a well written and thoughtful post about why Totoro is the best Ghibli movie ever, and meanwhile you think Totoro is not even in their top 3, then I would still recommend NOT downvoting 😃