These lists are in one way like old fashioned bibliographies, and in another like collections of actual books in a library. But they are in fact something new, a virtual library. A virtual library is created and maintained by a librarian or scholar who collects web sites in the same way a traditional librarian collects actual physical books and journals. The ability to discriminate between worthy and unworthy work is part of what any librarian brings to her job. After creating the collection, the virtual librarian must maintain it just as a regular librarian maintains a collection of physical books.
Links often disappear or move.
She must selectively add to her collection. At some point she may start to discard the oldest and least valuable sites. A good librarian will only add as much as she can maintain. It's a new concept, the virtual librarian who maintains the virtual library, but this is a service that librarians and scholars can provide in their field of specialization. With the growth of the virtual library, scholars and universities will be able to self-publish.