I don't think it's a coincidence. The Java ecosystem is intentionally isolated from the Unix ecosystem, because one of Java's goals was portability in an age when Windows, Mac, and Linux were all very different operating systems with very little in common. Java has its own Java-y build infrastructure, which relies much less on the concept of "trusting the source", and much more on the simple fact that the JVM is a sandbox that can be tuned to whatever security requirements the sysadmin desires.

Running Java apps (especially Docker-ized Java apps) is less like installing a Unix package (even if it's masquerading as doing so), and more like starting an instance of some untrusted VM image on your (software-defined-)network. It can use some of your computer's resources, but it has no permissions to touch any of your data or services unless you grant them to it. It really is like an app, or a web page.

Node/npm should get a mention. On a simple static website I've seen, a couple of grunt tasks end up pulling in over 14,000 files. And a hugely nested directory structure.

Part of it is the ... interesting ... idea that individual functions should come in their own module. Some npm modules are literally 6 lines of code. But they get packaged up just like everything else. There's no concept of having a stdlib or something. (Apparently node/v8/minifiers aren't smart enough to do a good job if you use a stdlib.)

I imagine they are just involved with the java ecosystem so the examples they know involve java.