To compare things we must be able to access them and if that access is to be efficient we must be able to access at a granular level. The things being accessed must be small and identified at that small level. We don't point people at a book of the bible, we point them at chapter and verse.
In TiddlyWiki speak, the tiddler is the granular piece. To make it truly accessible, to make it //useful// information we must give it a URI. We must make it a first class resource on the web. That's what TiddlyWeb does.