Sorry to be that guy, but I was less fascinated and more bemused by this one. Surely the origins of this would simply be somebody formalising the representation of “crossing something out”? An act as old as cave paintings, one assumes.
Can you find examples older than 100 years old that show a thing crossed out to mean "don't do this thing?" And how close are they to this representation? That's what the author was trying to find out.
