Polygamy? And why not? It's been a well-respected custom in a number of cultures.

People only object to things which they find unusual (or which are quite painful/physically harmful), generally speaking. If they're accustomed to something, then they find no reason to object to it.

Along this general line of thought...suppose we had had a custom in all human societies for the last thousand years to remove a child's left little finger just after birth? (And who cares why? People make up reasons for all kinds of arbitrary things, and then they obey them.) If we did have such a custom...I bet none of us here would have a left little finger, we wouldn't find that remarkable at all, but we'd be a bit shocked if we encountered someone who still HAD their left little finger! It would play merry hell with guitar technique to be missing the left little finger, of course, but I'm sure people would find ways to adapt to that.