There a few fences people stand behind in these types of arguments - similar to pickup changes, magnets, strings, hardware material - those who believe that changes can be heard, and those (often electricians!) who are certain that resistance is resistance. I am dead certain that old Centralabs sound different to today’s pots. Why there is a change is speculation but I’m guessing that material properties were different , like carbon, metals which influence not just resistance but also magnetic properties, frequency spectrum, acting as filters to the sound. The signal is so incredibly low to begin with, once you wack up an amplifier you will hear all the difference. If you blew up a minuscule ant to the size of an elephant you would notice that not all ants are the same ?