You keep using the term hypermedia and I'm not certain what is meant by that term (I was thinking it referred to linked media). Hyper means over, right? So is hypermedia more about the environment media is in than it is about links?
yes, I prefer the term hypermedia over hypertext because it stresses the systemic nature of a hypermedia system: a hypermedia (e.g. HTML, a hypertext), a hypermedia client (e.g. a web browser), a hypermedia protocol (e.g. HTTP) and hypermedia servers.
As far as what the term _hypermedia_ means: it is a media, such as a text, that includes within it _hypermedia controls_. Those hypermedia controls allow non-linear branching and interactions with the media, hence the term _hyper_, that is, above, "normal" media, which is consumed passively.
The hypermedia controls we are all most familiar with are anchors/links & and form tags. htmx attempts to generalize the concept of a hypermedia control.
The book goes into gory detail if you are interested in further exploring the idea.