Kevin, I understand your viewpoint very well.
I don't think anyone has intended to send anything but the best they are capable of!
Yet my experience with print exchanges are that mounted prints very rarely arrive undamaged, while unmounted prints are almost always fine.
I don't mount myself; there's a nearby framer who does far superior work to anything I could do without making a huge investment in time, effort and equipment. So any print I receive that's going up on the wall will be professionally mounted, matted and framed.
I prefer to sign the front of the print, outside the image area, and leave it up to the recipient whether to matt it with the signature hidden or visible, or not matt it at all.
I feel the requirement for a print to be matted and mounted to be considered "finished" is a particular USAmerican issue? It never crossed my mind until I read "the Print" that "unmounted" could be equated with "unfinished".
Just my two Ýre - a worthless coin that was removed from circulation several years ago.