I think it's a good idea to set a max on rewards. It's fair to get rewards based on content, not on the number of followers or people that upvote you.
I also think it would be better when this will be handled technically instead of by the community via downvotes or better vote distribution. Stimulating better vote distribution is good, but won't solve the problem because of autovoting and voting trails. Downvoting when it is a quality post doesn't feel very well.
Isn't there a way to technically implement a ceiling?