If an API has particular requirements, it should use HTTP features, or be described in the ToS. Saying "you must use this particular software" is a roundabout way of saying "We have opaque terms of service, changed at any time, without notice or consent."

Any need for virtual machines represents a complete failure of the modern operating system at its MOST IMPORTANT JOB: isolating processes and users from each other. (To paraphrase John Carmack)

I agree with your Hammer analogy. Once upon a time, Blockchain was invented to hit a nail, and it was immensely satisfying. Some people are trying to use it to hit babies, and that is not nearly as satisfying.

In other words, "{a}/{b}" can be parsed with the semantics of "{a}", for any {a} and {b} where "{a}" and "{a}/{b}" are both valid media types.

I wish media types were arbitrarily hierarchical... e.g. "application/json/ld" would be what we call "application/ld+json"; and "application/json/ld/problem" would be a JSON-LD document that is guaranteed to use the Problem vocabulary.