Worse, that connector was used on all sorts of things. That same connector was used for power delivery on some computers, midi keyboards, and monitor outputs. People blew up their sewing machine plugging a keyboard into a port. I'm sure there were more uses of that same connector for other things that were electrical incompatible. At least the PS/2 (and ADB) ports were used only for one purpose (PS/2 two - they should have either made mouse and keyboard interchangeable, or made them different, but just keyboard or mouse was a big improvement).
