Maybe it would be a small progress compared to now, but ...
Not enough people are down-voting so not enough organic content discovery is taking place.
... I fear that probably wouldn't really change: if then I would downvote (not flag) a whale because of "disagreement on reward" he would probably flag (or downvote) me because of "disagreement on my downvote". :)
And because his downvote would be many times stronger than mine I had to think twice if I dare to place my downvote at all (and this still would apply for every smaller account who intended to downvote an account bigger than himself).
However, I don't say your idea was bad ... just thinking ...