I'd disagree with that. In my area, the software dev population has just become segmented as different languages and tools became popular. When I started the JUG, there was an active Perl group and a Linux group but little else that drew a crowd. Now there is a strong Python group, 2 Ruby groups, a Scala group, a Clojure group, an FP group, a big data group, a Node group, Android and iOS groups, and probably a handful I've not even considered.

I know most of the other groups still draw smaller crowds than JUG, and there are several possible theories or justifications for that which have nothing to do with language popularity.

This of course is anecdotal and represents Philadelphia, but I'd imagine other locations have some similar experiences.