Natural counting isn't 1-indexed. You usually count things after you tally them, not before. (You don't start counting beans by saying "one bean" and then waiti

Natural counting isn't 1-indexed. You usually count things after you tally them, not before. (You don't start counting beans by saying "one bean" and then waiting for that bean to arrive.) Besides, it is not all that clear if someone just says "Jan 1 marks year one" whether it marks the end of the first year or the beginning. With dates, it usually marks the beginning. That's why it is 1-indexed. We hardly count anything else that way, so why would you assume it is 'natural counting'?