Reading the author's description made me realize how unbookmark-like bookmarks actually are. The current implementations are somewhat akin to creating a list of books that you like at the library. It's not so much a pointer to the information you found useful, as it is a list of books you found useful. You still have to do some digging when you go back for the book. If the book is lost, you end up having a reference to something that you cannot obtain. And if you just add books to the end of your list, you still end up having to search through the list. The only way around that is to spend time organizing your list. It's no wonder why bookmarks are useless to so many people.
The author doesn't really solve the problem with bookmarks, except for one. The last one. By sticking a bookmarks file in a project directory, at least you're only searching through a list of bookmarks relevant to the project. If you are no longer interested in the project and delete it, you're also getting rid of bookmarks that you (hopefully) no longer need. It also addresses the portability of bookmarks. As far as I can tell, the only way to move bookmarks between any of the major browsers involves the use of special software or network services. Look at moving bookmarks from one Firefox installation to another: you either use online sync, export to HTML to import from HTML, or import the database (which replaces your current bookmarks with the ones being imported).