Actually the answer is in all of us.
It is decentralized as you mention prior.

This is called trial and error.

1.- The same way your ability to vote drop after certain amount of vote, it should go down with the amount of posts and most likely rewards accumulated with that post. Something has to give. I know it has to do with bandwidth then
2.- There should be a bot on steemit after three posts with a certain amount of rewards. Again it is decentralized.
3.- Whatever ideas I bring, it will be biased to my belief system. This is human factor.
4.- There should be a break system match with steem value to curb abuser from the system. That way it is immune to all steemians and protect fairness and prosper the longevity of the community.

At the end, keep on steemit.