I remember the user called likwid (I intentionally omitted the @ tag to avoid notifying them) who said at one comment that they automatically downvote users whose downvote mana is at 100%. While they want to enforce the same rule that you want, I strongly disagree with their "punishment" of downvotes that will not only reduce your rewards, but also your reputation. Nowadays, they went further as to downvoting posts about entertainment (and upvoting only posts about cryptocurrencies).
That said, my opinion on this matter is that I don't want users be forced to downvote others, just because of the "stigma" that downvoting a post means that you hate the post (or the poster). I believe that every user has all the rights to their own Hive account(s), which means not using a power when they don't feel like it.
Just for you to know, I personally like using my downvote mana to reduce the rewards of spammers and obvious autodownvoting (for no reason) users (such as mmmmkkkk311).