With costs of distribution getting smaller and smaller, it becomes easier to have a distribution model where most people get the digital product for free. Building up a large network of free users can help make a platform viable for paid users. Psychologically, mircropayments have not worked well (since there is a huge cliff between "free" and "pay") However, instead of charging everyone 1 cent, 1 person can be charged a $1 and everyone else can get it free. This allows building a large network or following (which also adds value to those who pay.)
The book is an interesting read, with many ideas that now seem obvious. Free can be a promotional tool as well as a valid business model.