[Rusky]

The JVM was designed as a compile target for a very particular kind of language. One with a Java-like object model, with some later concessions for more dynamic languages.

C, C++, Rust, etc. do not fit into that model at all. There's a lot of software written in C, and there's a lot of performance to be gained by dropping down to that level when necessary.

[fulafel]

By later concessions do you mean invokedynamic? How much did it help? Clojure doesn't use it even now, 8 years after it came about, I think. Is it mostly for JRuby?

The JVM is (and was from the start) a lot more dynamic than Java.