I do wonder though what a better alternative might be (and if this has been studied at all). It's fundamentally an issue with people being emotional and often quite bad at separating their own personal feeling from their voting. I know some platforms simply disable downvotes, which partially solves the issue, but at the same time, I think there is some value in communities being able to downvote spam or genuinely poor content. Maybe if you had to also make a comment - thus upping the amount of effort required - it'd be better?

Kbin does also have the quirk that votes are actually public, so you can actually tell if someone is following you around downvoting everything. That could potentially be seen as a rule violation and lead to being banned from an instance.