The reality is that downvotes are never going to fix the excessive rewards issue. It may have an impact on plagiarism, and new account spammers, but never on excessive payouts. I just did a check to remove $10.00 value from a post you need 500,000.00 SP that's five hundred thousand Steem Power. At 100% your downvote in that case would be ten dollars. The example post has a payout of $168.00+. With out the ability to decrease the reward givers vote/curation reward then the downvote is meaningless and only has an effect on smaller accounts.