That's not what's happening. Using your analogy, you're reading the book, remembering it, and then making N more books (maybe for commercial purposes) by using

That's not what's happening. Using your analogy, you're reading the book, remembering it, and then making N more books (maybe for commercial purposes) by using what you remembered to create something very similar in terms of style, prose, plot, and so on. As a result, the person who you learned from can't get a job writing anymore because their work has been commoditized. Also, they're feeling lost because the work they devoted their lives to is now awash in a sea of similar work.