This pretty well sums it up:

In days past, these professional courtesies were almost necessary in building a strong agent/client relationship. Those days are long gone. At one time, it was a loving and trusting relationship built on mutual respect. But as with most modern relationships, the agent/client, once sacred bond, has been destroyed by the Internet.

I like to say that the intermediary must love both sides; that gets harder to sustain in a hurricane of disintermediation. Craig’s list and eBay don’t sport much relationship. Amazon’s model of your buying habits is the best you’re likely to get along those lines.