The whole site is based on incentivization, so what you're proposing should be common sense.
I think a lot of smaller accounts are afraid of being flagged. Maybe the middle-sized accounts are feeling the same, as they can actually be hurt by being added to a flagging bot list (or something).
It's hard to predict why people do (or don't do) what they do. Being incentivized is a serious game-changer, but is SteemIt doing it right? I'm not sure. Perhaps there's a more effective way that doesn't inspire self-voting, bots, spamming, and plagiarism.
I guess SteemIt is still technically in beta, so we should still be figuring it out and calibrating. I really don't know lol.
Many people make valid points about flagging, but my theory is that if Minnows flagged the minnows, people would be trained by the time they had much stake.
And yeah, I agree it is hard to predict, but a management team with the Authority to makes changes could make them quickly, I know this, because it is what I do. I evaluate companies, talk to employers and customers and advise them on how to change the culture.