I believe that part of the problem is that links do not work so well for that initial intent; and that is (IMHO) because of the coarse granularity of that that can be linked; while theoretically you can link to anything with a URI, effectively they usually just point to documents and anchors of some of their parts. And that capability must be provided by the author, so, as the problems with the semantic web, most of the authors do not have incentives. So you are precluded from slicing and dicing content from others and, as Ted Nelson wanted, transcluding that part of another person's train of thought into your own document.
So we repurposed the "link" tool to just navigation.
Perhaps if we could add linkable annotations on pages of other people then we could play easier with other people's ideas...