That's kind of my point. Does the JVM really need four different general purpose languages with their own ecosystems to split the JVM ecosystem and userbase?
Why not? There's like 483 different application frameworks for the JVM too. The more choices the better - it lets ideas cross-pollinate, and the best ideas get borrowed/stolen. Some people like different syntax, bindings, etc.
I find the opposite more troubling, actually. Take the C# ecosystem and see how there's one de-facto application framework (.NET), one logging lib, one etc... It's usually Microsoft's way or the highway, and 3rd party libraries and frameworks struggle to get any adoption. Consequently, that ecosystem is much smaller, less diverse, and less innovative.
I dunno... Scala, Clojure, and Groovy users? Small user bases, but the languages are not dead.