comp.lang.lisp has long lost any importance. Most Common Lisp users have moved on. The communication infrastructure shifted to the mailing lists ( http://dir.gmane.org/index.php?prefix=gmane.lisp ) and the #lisp IRC channel. That's where the real work was done. Even much random talk now has been moved since quite some time to reddit / lisp, stackoverflow, planet lisp and even Twitter #lisp.
comp.lang.lisp is long dead.
Indeed, comp.lang.lisp is now irrelevant; but it wasn't irrelevant at the time Erik retired from it, despite his strenuous efforts.
However, I wasn't talking about only Common Lisp users, but about users of all Lisps. Elisp and Clojure have similarly-sized Freenode channels #emacs and #clojure, each substantially bigger than #lisp. Various estimates of the number of Emacs users put them around 5–50k people: there are perhaps around 15000 Elisp users http://stackoverflow.com/questions/3311227/emacs-user-base-s... or 0.5% of Ubuntu users using Elisp http://programmers.stackexchange.com/questions/35312/emacs-u... (some tens of thousands) or 5300 Github users with Elisp repositories http://www.quora.com/How-many-people-use-emacs-per-day?share....
How is using an editor making them Lisp users? Are users of Google's flight search engine, written in Common Lisp, making them Common Lisp users? Are AutoCAD users Lisp users?
How many Emacs users just use it? How many already need help to configure .emacs ?
Typically AutoCAD users are not AutoLISP users. (By the way, AutoLISP conses are also immutable, although you have complained that the immutability and resulting "persistence" of Clojure lists counts against calling it a Lisp.) But typically Emacs users are indeed Elisp users, because they read, write, and modify Elisp code. That's why there are several thousand Elisp repositories on GitHub.
comp.lang.lisp was very important prior to the founding of Stack Overflow, EmacsWiki, and so on. It was a lot more important to Lisp than any Lisp company, and maybe more important than all Lisp companies put together.