A registry would be useful but it should not be the only way to name libraries. A registry forces authors to register their libraries for every new library they want others to use. But that can become a rather tedious process, especially if you are into rapid development and sharing a new idea “right now”. I want to put the library up on my github account and share the link… a 60 second process at most.
+1
Last I checked, Racket requires new packages to be registered in order to download them using their "raco pkg" tool. The registration process is completely automated, and it's very painless and nicely done, but it'd still be nice to be able to skip it if a geographically distributed group of people is working by themselves and doesn't (yet) need to share their work.
npm (node.js package manager) arguably shows that it may not even be desirable to publish all libraries people write in a central registry. With too many of them it becomes difficult for users to figure out which ones are polished enough for serious use.
Collections like snow-fort, Akku, Chicken eggs and Emacs MELPA strike a good balance between quality and comprehensiveness IMHO.