For me, this whole concept came about because of Bresson. He was alleged to have printed full frame. The people that were influential in my photographic life at that time were proponents of composing full frame. For a commercial shooter or a portrait photographer, I would think it is not something that would benefit them.
When I look at cropped images, I think I can tell the difference in a cropped and uncropped image. For me, it has to do with the aspect ratio, I think. The images looks different than it would uncropped.
edited for spelling errors