They did. I think the idea with XML based hypertext was to have links that are star-shaped with potentially multiple sources and potentially multiple targets and the location where the link is defined completely independent from any sources or targets.
One application would have been that people publish link collections and you could e.g read HN with the links I created.
There was a proposed standard for this but its name escapes me for the moment.
Of course all of this never went farther than XHTML where it took a sharp turn into a different direction.
> There was a proposed standard for this but its name escapes me for the moment.
XLink? It supports a feature known as extended links, which seems similar to what you're describing.
Multi-link QR codes could be practically useful, provided an interstice appears with the URLs and allows a person to follow any of them or all of them.