I didn't know about JSON:API, thanks for the pointer. It seems to tighten the JSON responses a bit, but doesn't address linking or extending vocabularies though.
Thanks for the link to the discussion on Github. I don't think it is a good idea to rely on inference (owl:sameAs) for something as basic as foaf:name vs. rdfs:label vs. schema:name, ...
I have not used JSON API yet but it is cool to see the "follow your nose" approach be applied to REST APIs.