I think this actually roots in the problems of conversion to base ten from base twelve. Not sure though, maybe I remembered this wrong.

Being lazy and not going to look it up. I can’t help it to wonder if it’s also based in Sumerian’s base 60

It's base 20.

80 in French is 4 x 20. A long time ago, 60 was "trois-vingt", 3 x 20. We still have a hospital in Paris called "Hopital des Quinze-Vingts", 15 x 20 because it used to have 300 beds.