It may be optimistic; many optimistic things with only a small chance of working are still worth a try. (Assuming the worst, and designing only for the worst, then ensures the worst.)

That 'spite' you mention isn't a constant across all communities, across all time: it grows with cycles of negative, stinging punishment-feedback. (The study which started this thread was suggestive of that, regardless of its other limitations.)

I strongly suspect each of the following is true:

• threads on certain contentious subjects have lots of competitive and retaliatory downvotes, driven from the impulses "I can't let only these favored comments sink/fade" and "if those partisans are downvoting me, I'll downvote them"

• that habit/mood, once learned, spills over into other threads, to the detriment of discourse and positive/productive feelings

A separate axis for disagreement might catch some of that and express it where it does less spite-generation.