I believe the author's point is that there are just too many books out there. Book reviews and ratings saves you time by helping you avoid the bad ones to begi

I believe the author's point is that there are just too many books out there. Book reviews and ratings saves you time by helping you avoid the bad ones to begin with. In that case good star reviews does matter. The reviews helps you avoid those books that you mention in your example. Though I agree that reading widely does help, it makes sense to focus your limited time to read and use sources that have been thoroughly reviewed by other people