There is some good stuff in here, but it misses the biggest pain point developers face when trying to make a robust hypermedia API: tooling. There is a lack of tooling on the server side and almost no tooling on the client side. The amount of effort required to serve a RESTful API requires a lot of upfront investment. Then convincing the client developers to take advantage of the hypermedia affordances requires a lot of time and energy. If one does manage to convince them, the client tooling requires even more upfront investment. The only attempt at client tooling I have seen is the work done by Mike Amundsen.

One thing GraphQL got right was focusing on the client tooling. If the client developers are bought in to the protocol/specification then the server developers will naturally come along. The reverse has not been true in my case.

This opinion is based on my experience building hypermedia APIs, consuming hypermedia APIs and helping with the HAL hypermedia spec.