I think this is accurate (in terms of exposure, not that it's hardly used). As soon as it was possible for other languages to run on the JVM, the huge amount of developers working around JVM infrastructure that didn't like the sometimes painful experience of working with Java, started looking at alternatives.

Groovy, Scala and Clojure were the early contenders that people were exploring and Clojure seems to have won a lot of mindshare.

The thing about Java isn't the language or the JVM it's the App Servers. Enterprises have invested heavily in the App Server infrastructure for deploying JVM based code from monitoring, training, etc.

Throwing all that away to use a non-JVM language is a REALLY hard sell. Those app servers are very well done.

Running on the JVM made using Clojure, Scala and Groovy possible in places where other languages wouldn't have been. In the early 2000s, it was Java and everything else.

The .NET ecosystem was awful at that time. The programming world was essentially, Java, Perl and PHP 4 in terms of enterprise usage. People said the words "Enterprise Java Beans" without a chuckle.

People were HUNGRY for better options.

Now you've got a solid C# ecosystem, Elixir, Go, a dominant Python ecosystem, significantly more polished PHP, K8's & Docker that make automating the infrastructure around all different languages consistent...it's just a different world.