"Disagreement over rewards was always a dodgy reason in my opinion."
Interesting.
I always thought of that as one of the more legitimate reasons, as it speaks directly to what a downvote does mechanically. I can't say I've done it much for that reason, but when obviously low effort posts get huge rewards it makes some sense to me.
I'm pretty loose with the downvotes though, at least philosophically. Practically speaking the vast majority of my votes are upvotes.
I'm glad to see a diversity of opinion here.
Admittedly, sometimes it's pretty obvious when a post is over rewarded, but it can be hard to draw a line.