busy, dtube, steepshot all take a % as a beneficiary for their service layered on steemit. It may not be obvious so I agree it should be clear. However you will also find posts on steemit talking about getting more viewers by using those platforms so it may be a wash since you make up for it in volume once you get more established. In the early days it is harder for sure.

edit: dlive does not charge, I was mistaken