Davey, I know quite a few sellers who don't know what their houses are worth, so they ask a broker, the market expert, to suggest a price. Sure the seller is free to accept or reject it, but often the seller is relying on the advice of the "professional". In this scenario, can you not imagine the broker suggesting a price that is more likely to sell quicker than a slightly higher price which would benefit more the seller?
This is like my relationship with my lawyer whom I hire for evictions. He is the expert, so I pay him to offer advice. Sure, I have to approve or reject that advice, so I am "completely" in control, but he knows more than I do, and could easily take advantage of that disparity of knowledge and experience. In these kinds of relationships, it is easy for one party to take advantage of the other. Same with construction contractors. It is easy to say that the client is in control. He is, but that does not mean that the hired professional will not put his own interests first. Buyer beware.
Peter, I don’t know the brokers you are talking about, but I can tell you this is not the way the business should be conducted...and IME this is not the way things are conducted, at least in my neck of the woods. If you wish to discuss this further, I think we should do this by PM.