Web Documents are More Navigable
Web documents contain built in navigational features. The Web encourages and supports movement to other pieces information in multiple directions. For instance to access information quickly in a book you look in the index and then flip to any of a number of pages, if the information you seek is not on that page you go back to the index and repeat the process and until you find what you're looking for. With the Web this process is condensed significantly, you can "flip" pages instantaneously with a click of the mouse.