This is a pretty neat idea and I think something like this could easily be implemented in the future by some of these promotion company styled accounts.

As mentioned in the revision an other comments I was viewing this as these people helping under guise as altruists and had not really considered an underlying business aspect of it and how it was helping their clients.

What future promo authors decide to agree on for compensation is between them and the clients they reel in. While I think some of the rates charged in the past may be a bit costly I do see the need for their existence now.