I have mixed feelings about post promotion. My main concern is that successful Steemit users (those with the means to promote their posts) will continue to gain more success for themselves while post promotion won't help those who really need it. Like you said, "the rich will get richer."
But I guess that isn't inherently wrong. And maybe it won't turn out that way. Maybe I'm just getting jealous of those who are finding real success on the platform haha
I'm only very new to Steemit but the way I'm beginning to see it, is that it's such a fair rewarding system. Quite karmic in that the energy you are willing to give will come back to you ~ May not be the way you expect or in the time you would like ~ But in some mysterious way you will be 'heard.' And all you have to do is enjoy sharing what is close to your own heart and look at and comment on posts that you resonate with. This may be a tad on the naive side, as I'm still not familiar with the power and inclinations of the whales.