I'm glad you asked that, Avnesh, because you've touched on a veyr important RC principal: always distinguish between the views of other people that are merely being reported by the author. Here, the author says things like "proponents of theory dispute" and "critics of theory A... argue." So the author is not taking a side and refuting an argument, but is instead discussing the views of people who hold different theories. In other words, the author is describing two sides of an argument, rather than making an argument.
1 Explanation