why isn't json-ld used for rdf vocabularies other than schema

Question

I am relatively new to rdf and semantic web in general. I am seeing that there are a few different syntaxes for embedding rdf data in web pages/expressing rdf in general: microdata, idfa and json-ld. Each, supposedly, fully compatible with any rdf vocabulary.

But in practice, I don't see this cross-compatibility. The only exception to this seems to be schema.org, whose vocabulary can be expressed in each of the aforementioned syntaxes. Other vocabularies, such as opengraph, dublincore and rss, never seem to be described using json-ld.

My question is, if I were to add, for instance, opengraph metada to my website using json-ld syntax, would this metadata continue to work and be useful? Or would it be ignored by whatever entity scans my site for opengraph metadata? Same question for other rdf vocabularies.