Yeah... they're trying to do with certain ebooks, largely. That's got a hell of a long way to go in terms of sophistication, from what I recall, though, and the existence of physical copies are massive, gaping, holes in the defenses, so to speak (at least until they come up with economical paper that prevents or interferes with scanning, I guess. And even that leaves flat copying by hand.). But even physical books, at least theoretically (if not economically or actually) have DRM-style methods available. Apply the general technical field behind paper currency to a book and bob's yer uncle.
Plus, as large as the FOSS or even just free movements are in gaming, the similar sort of thing in terms of writing is exponentially larger (though perhaps only absolutely, not relatively.), so... there's, like, a greater body of great works in literature for people to turn to if commercial stuff gets too uppity.
Though... it's not untrue that you can have a pretty darn robust gaming experience without resorting to commercial works, especially if you include commercial works that were eventually released publicly. The sticky thread should be monument enough to that, heh.