A book is not part of an author, it is not their baby. A book is a story that a person created and released out into the world to exist as it's own entity.
A reader of a book is not rating a person who wrote a book, they are not rating that person's baby. A reader is rating THEIR experience while living through a story.
The author might be mentioned even attacked but only in terms of how the author's telling of that story affected THE READERS EXPERIENCE.
Readers are so varied and unique, bringing their own varied and unique lives and integrating them with each reading of the story, and in that way each reading is a unique story completely separate from the authors original telling.
Authors attacking readers is as logical as the subject of math attacking a student for disliking it.