[antiterra]

There's value to some creators in having a marketplace in order to get exposure and to provide a convenient browsing experience for customers. Independent musicians who give away their music for free are often grouped into netlabels[1] so that people can find them and discover other works that are somehow related.

A large portion of applications on the Mac App store were and are available directly from the creators, but plenty of authors elected for a presence there. More independent models, such as Cydia and Ubuntu Software Center still take a cut of sales.

Review sites might be one way around the issue-- say, if it was possible to browse GoodReads and every book you were interested in had a link to whatever distribution method the author chose. But then, if GoodReads was the go to site for books, it might start charging a cut too, or prioritizing sponsored links.

[1] http://en.wikipedia.org/wiki/Netlabel