A flag is a downvote... which is confusing because a flag should be 'this is inappropriate'. There are moves to update the code to have a downvote button next to the upvote button. A flag/downvote also takes away from your voting pool, so you basically have to choose to upvote something you like or downvote something you dislike/think is getting more money than it should.
I saw another plan to allocate 10% of everyone's voting power purely to downvoting, which I really liked... it means that if you didn't want to downvote yourself you could donate that 10% to Steemcleaners which would dramatically increase their effect. Not sure if this plan got approved though.
that is a pretty cool idea, where did you see that post at?
https://steemit.com/steem/@transisto/separate-downvoting-power-pool-concept-visualized