Earlier quoted context omitted.
How was the CDL hurting working authors? A library bought the book, paying the publisher and the author. The IA scanned the book for digital lending, this digital copy could only be checked out by one person and only when the physical book was not also checked out. I understand the court decided this wasn't okay. That aside, how was it hurting working authors?
Because other libraries have licensing agreements that benefit authors on a different basis than "you sold one book to one library". You may argue that that shouldn't be the paradigm, but one library unilaterally changing it denies the authors their say on the change, either through licensing or legislation.
It benefits the publishing megacorps on a different basis, authors make very little on book sales or loans.