Note: I don't actually think this should be implemented because I wouldn't want to encourage more down-voting. But those who do want more downvoting of disliked users, might find it interesting.
I was thinking about Steem and how I've heard a lot of people complain about policing content and self-voting.
Currently down-voting is self-destructive because there is no chance of a curation reward but it still takes away voting power. There is an opportunity cost associated with down-voting.
One idea I have to counter that is reverse curation rewards. This is basically the idea that you get rewards for downvoting something that later gets downvoted a lot more.
I imagine it working in a way where positive and negative curation rewards run parallel. So for example say we have a post which gets +$10 but also -$10 in downvotes.
The author reward would be canceled out to $0. But the curation reward would take into account the full $20 of voting power used.
$20 * 0.25 = $5 authors reward
$2.50 in upvotes to be distributed among the up-voters
$2.50 in downvotes to be distributed among the down-voters.
This setup would recognize the power cost of both up-voters and down-voters and reward the subjective curation process of both sides. Another example:
$5 in upvotes
$2 in downvotes
author gets $3 * 0.75
upvoters get $5 * 0.25
downvoters get $2 * 0.25
Of course this system inherently will increase the amount downvoting down on Steem. This could be a good or bad thing depending on who you ask.
There is probably a psychological reason behind Facebook not even having a downvote button.