Sounds good and thanks for the clarification. I don’t have any opinions about polyglots, in general, but it is a tough position to defend that AP JSON-LD has been successful (not saying you are doing that, but it’s a general comment). Success and failure are not necessarily either/or, but AP JSON-LD seems pretty close to the failure side of the spectrum to me (in terms of actual deployment and success in the wild, not in theory or concept).
Maybe a specification cleanup is all that’s needed to make it a success, but my gut and observations tell me the issues probably run deeper than that.
I also think that it may have been a mistake to believe “extensibility” came for free with JSON-LD and then mostly ignore the topic during the specification process. It depends on what one means by “extensibility”, but I think JSON-LD supports only a very weak form of it (primarily namespaced property names). That alone is not enough for effective interoperability, in my opinion.
If a SocialWG (AP-focused) were starting greenfield today, with the benefit of what we’ve learned over the last 5 years and knowledge of current federated server deployments, I wonder what different choices they might make.