Your argument would make sense if our system were actually base 12, or if we actually worked in halves or thirds of feet. Or if we ever had a reason to convert

Your argument would make sense if our system were actually base 12, or if we actually worked in halves or thirds of feet. Or if we ever had a reason to convert feet to eggs, or feet to hours. No, the base changes for every unit of measurement. Inches are divided into 16ths, feet into 12ths, yards, into thirds, miles into 1760ths. Inches are the worst as the base changes depending on how accurate you want to be, or if the fraction can be simplified, 3/8ths 7/16ths, 15/32nds. And of course all of the numbers used to count them are base 10. The metric system uses base 10 all around. Not because we have 10 fingers, but because that's the system most widely used.