As an add-on to Solveig's comments: an important way in which both musicians and writers build careers as artists is through the backlist. They keep working, and hope that each new product will add to their audience base, and that those who like the latest will then want to acquire the whole oeuvre.

So if a system requires that the initial works be given away irrevocably, it eliminates this strategy, and makes the already-almost-impossible task of making a living as an artist even harder.

At a music conference I attended last Spring, one artists' manager noted that from his point of view the worst thing about the unauthorized P2P sites was not that they spread the current hits but that they absolutely killed his backlist, which devastated the efforts of his clients to build careers over time.