You have to think about it from the author's perspective. Many authors are not interested in the minutiae of the process, and the publisher serves as a single

You have to think about it from the author's perspective. Many authors are not interested in the minutiae of the process, and the publisher serves as a single point for the author. There's no need to deal with a separate person for market and a separate person for physical distribution. There is a value (albeit small for some people) to bringing the disparate pieces together into a single package, freeing the author from the need to handle these pieces. FWIW: I wish the people performing this service in the financial industry weren't gouging customers ...