The main hack these commodification entities makes seems to be to disrupt the traditional flow of information and valuation, then create a new marketplace it controls. For books, I imagine many centuries ago the literary class wrote and read books largely from the social and intellectual forces at the time. The smallest unit of these interactions would be a member reading a book, liking it and recommending it to his friends. The net aggregation of such would slowly produce a trend, communicating to writers that there was a higher chance of being read if you followed it. Now such exchanges have been consumed by digital marketplaces. The sheer size means writers have to make a Faustian bargain to bend to it's needs, while readers have a curated list of books for them. Any well reading writer and reader have an impossible time communicating because the main flow of information has been hijacked.