I'd sum it up in terms of "standards bodies / enterprise would be perfectly happy if everything were ossified in a form that encompassed all possible use cases,

I'd sum it up in terms of "standards bodies / enterprise would be perfectly happy if everything were ossified in a form that encompassed all possible use cases, regardless of complexity." Whereas reimplementation in a lighter weight protocol is usually the result of "devs don't want to deal with the above when it isn't needed for 80% of common use cases."