Think of it like ML at the human level. ML's entire thing is statistical correlations that aren't obvious. Tradition is probably operating like that as well.

Think of it like ML at the human level. ML's entire thing is statistical correlations that aren't obvious. Tradition is probably operating like that as well. Is all tradition like this and useful? Of course not. But I bet a lot of it is very subtle and nuanced. It's also worth considering that there are other pressures. For example, women typically find circumstanced penises more appealing. It's very possible that pressure, coupled with the benefits, helped society land on it more than not.