I think I’ve settled on the latter. Disagreement is maybe best communicated by the absence of an upvote? And downvotes work best when they signal something that is just off base, and while not reportable, is not appreciated at a broad cultural level.
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 😃