I think it's the JVM that's the real win for Java. At my work we have a mix of Java, Kotlin and Scala and they all Just Work in our deployment pipeline that was built with just Java in mind.
On the other hand, they need to have everything. In many other languages, it's common to just use a library written in a different language. For some reason, the foreign function interface of Java seems to have been designed to be hard to use, so instead of using an already existing library, Java developers tend to go through the route of "Rewrite It In Java".