I still cling on to the quaint idea that "upvote" means "adds meaningfully and coherently to the discussion", while "downvote" means the opposite. So not "I agree with this" or "that made me chuckle" but rather "this enhances the conversation" - and especially if it's a well written argument I disagree with because that might make me learn or rethink my position. Humour in a well argued point is very welcome, of course.
Wish and reality aren't in alignment here but some places like HN or /r/AskHistorians are my refuges.
That's not how it works at all. In general I've noticed that many of the things I say might remain neutral or get some upvotes, and then get flagged and downvoted as soon as the USA wakes up. So I think here it is very very much based on agreement.