Mainly because unless it's a business requirement, developers that work with the internals of software (so not just some CRUD layer and protocol that already ha

Mainly because unless it's a business requirement, developers that work with the internals of software (so not just some CRUD layer and protocol that already has been abstracted) prefer to use things that feel good and look nice. XML for example isn't one of those, it looks like a mess. Granted, anything can be made to look like a mess, but it seems that JSON is much more enjoyable than XML, and such preferences tend to make a whole lot more impact on what is going to be used than technical/academic prowess. Applies to most things, and factors in to what kind/type of person you get when you talk to developers at a startup, a bank, general commerce, a FAANG or a technology provider. Not everyone seems to enjoy the kinds of people that "exclusively write complex systems software" or "exclusively write business software for the money" just like not everyone likes "exclusively writes software because they enjoy it", and that's fine. But it directly impact adoption of stuff. URNs, URIs, and UTIs (and UBL) are all fine examples of technology designed to solve a thing, but also fine examples of not getting the adoption you'd thing it gets when it is "technically correct".