Those other runtimes also don't do half of the features a JVM usually has to offer, and most people complaining also don't bother to actually learn the Java ecosystem, the existing set of JVM implementations, and the optimizations features made available to them.

No, that's defiantly true in other non-native runtimes.

E.g. any Python project has to deal with this, like Mercurial.

Java projects tend to (insert stereotype) have a lot of code.