In my opinion, some individual ADs seem to, from their behavior, feel that they have not done their jobs unless they have raised a "discuss". The one that took the cake for me personally was a "discuss" raised by a particular AD (who shall remain nameless) that in essence wondered what he should raise a "discuss" about in my document. There were a couple of errors in that; he told me later that what he had done was opened the comment tool and typed that question, and subsequently accidentally hit the equivalent of "send" - the question wasn't intended to go out. But the question itself is telling: the issue was not "does the document meet the requirements of BCP 9", it was "what comment shall I raise"?
Also, in my opinion, IESG review that raises a certain number of issues should not result in the document sitting in the IESG's queue for a few months while the authors go back and forth with the AD or the GEN-ART reviewer pounding the document into someone's idea of "shape" without working group involvement. I personally would prefer that simple matters get sorted out between the ADs and the author, but complex changes or additional content requested by the AD should result in the document being sent back to the working group.