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 withhold downvotes until it means “this is disinformation, or misinformation so wrong-headed it could mislead those new to the topic”
Same, and also “this has already been said in this thread. You should have upvoted the existing comment.” Basically a tool to improve signal-to-noise ratio of the discussion.