In fact, acquiescence/"a requirement" has been the norm for about 5,000 years. Unless you think humans operate under the rule that anyone should be able to call anyone else what ever the caller wants to their face. So I can call, for example, any one of a different race whatever I like, name-wise. Or the king "DIckface." Or your mom "Shitbitch."
It's really not that complicated. I have never understood the kerfuffle. In my view, those who argue this point are the ones with a mental health problem. There's no "law" because only the deranged would do, or make a habit of doing, otherwise, IMO.
You call people the name they ask you to. You have done your whole life. Period. End of discussion. And you're respectful until Mr. Jones tells you it's okay to call him Henry.