Two Authors "Duke it Out" in a Bookstore

Recently, I’d been checking out some biographies about Ayn Rand. Two of these in particular are fairly critical of her, emphasizing her flaws and “humanity”, while another expose attacked these in turn.

What I find most interesting is the comment section. Generally this is where readers go to review the books, and to offer criticisms. In my experience and opinion, these criticisms are often of “high quality”, and influence my decision on whether or not to buy the book. With my (and many other individuals’) money on the line, it’s not surprising that arguments form, not only between the critic and the book, but between critics themselves. However, I was somewhat surprised by the given exchange presented in the comment section between the book’s author (Valliant), and another author with a competing viewpoint (Parille).

Sticking with the analogy of “amazon as bookstore”, the purpose of the review section seems to have changed from:
A) a place where book enthusiasts can go and leave notes about the books they like… much like what happens in a casual conversation at a bookstore.
to
B) a place for informed criticism and philosophical debate over the content of the book.
to
C) a place for authors to criticize each other’s content and launch barely concealed ad hominem attacks.

So, as the authors pick themselves up and dust themselves off in the aisles of Amazon Books, I’m wondering if this process is “better”, or if the notion of a comment section is being hijacked and used inappropriately… I’ve got no conclusions though. I like hearing people’s experiences reading a given book, but I also like a good mudslinging