For an argument against using JSON-LD, see https://hsivonen.fi/no-json-ns/
It may be read as an argument against making namespaces a ubiquitous part of JSON, in the same way as they are ubiquitous in XML (even though not part of the base XML spec). It’s a valid argument against getting to the point where namespaces pop up in every JSON tutorial, and every JSON serializer takes a namespace map, and every user of JSON has to deal with them.
But JSON-LD (as RDF) uses namespaces to solve a particular problem (merging data from disparate sources). Solutions involve costs, that’s normal. You might weigh this cost against the expected payoff and decide it’s not worth it for you — but the article doesn’t do that.
https://groups.google.com/forum/m/#!topic/mozilla.dev.platfo...