Yeah, but it doesn't make up for the decade+ now that plain JSON (perhaps with the occasional URL, which still has to be interpreted correctly by client code!)

Yeah, but it doesn't make up for the decade+ now that plain JSON (perhaps with the occasional URL, which still has to be interpreted correctly by client code!) has been called "REST-ful". On top of that, JSON-LD is still mainly focused on networked object graph serialization. Unfortunately it manages to be a complex specification without providing the functionality that HTML came with out of the gates as a hypertext in an obvious manner. HTML is a good-enough-to-great hypertext, we should probably stick with it.