We used to say in seminary,”You’ll find the text sheds great light on the commentaries.”
I would think that would be more true as a factual check, or if the commentary assumes knowledge on the part of the reader that isn't there. However, I wouldn't expect a primary portion of text to serve as an explanation of an explanation of that same portion of text. If it was, it would seem that the commenter has missed his target. :) I don't know, maybe if I had an example I could see what you mean.
Good to see you again my friend.