It isn't promulgated primarily by historians studying the Middle Ages. It's promulgated primarily by classicists, and in truth held by the majority of academic historians, and I'm willing to believe widely by medievalists.

The author shouldn't have made such a pat assignation of blame. But, erm, I was supposed to subsume his (in my view flawed) sorting argument into my thinking, and not having done so shows I didn't read the piece? How odd.