I am totally agreeing with you but

You use the payout downvote option when there is an issue with the perceived value of the post - and there is no flaw related to the post itself or its author. Instead, this is a legitimate part of your curation efforts.

think about all those other posters hunting a trending rank that will payout downvote everything else. And there is created spam/troll payout downvoting. I can safely assume that more than 50% of the authors and newly backed users will do that.

And another but: this payout downvote can be countered with some account filters like:

• account older than xx days (weeks, months, whatever) not hours
• account power higher than xx vesting shares
• account value higher than xx
• voting power higher than xx%
• post count higher than xx posts

Filtering the downvote rights will make it a bit more safe for the community.