Earlier quoted context omitted.
If you're going to get that picky (and please be aware I'm only doing this for the sake of the argument) media can never be hypermedia in the absence of the client. HTML opened in notepad is just text. Cat GIFs, rendered in the correct client, would absolutely be hypermedia (you could inline link data as QR codes, if you felt like being perverse). Hypermedia starts with the client, not with the file format.
I agree that a hypermedia can't act properly within the uniform interface constraint, without a hypermedia client, that is, you can't have a hypermedia system without a proper hypermedia client: https://htmx.org/essays/hypermedia-clients/ https://hypermedia.systems/hypermedia-components/ On the other hand, there is a real difference between plain text and HTML (or HXML, don't shoot!) which is a subset of text with ad…
So, HTML is different from plain text because it "has concepts layered on top of text" where as JSON is not hypermedia despite "having concepts layered on top of text". And the only reason is because you said so.
> So I still think it makes sense to discuss if a media is or is not hypermedia without reference to the client
Then JSON is just as much hypermedia as HTML. Both are structured text unusable without a specific client to display them or work with them.
> Semantic nitpicking perhaps, but then hypermedia discussions appear to tend to invite this sort of thing.
They only invite them because of your insistence on calling only HTML the "natural hypermedia" etc.