IMO, the biggest reason is how broken the Java ecosystem is. Java-the-language is mostly okay, Java-the-toolchain (JVM) is pretty great, but Maven/Gradle/etc. are awful.
Java is one of the few ecosystems that provides a software distribution ecosystem that doesn't allow distribution of sources alongside binaries. Additionally, it is a lot more common for Java dependencies to be a game of Jenga. Take for example, Gradle. Gradle literally cannot be built from source[1] because it relies on a binary cache of dependencies held by Gradle to build Gradle. There are many other examples of this. As a consequence, the Java ecosystem has become a security and maintenance nightmare that other ecosystems simply aren't.
As bad as Nodejs is, it doesn't do this. As difficult as .NET has been, the dependency hygiene is better there. As annoying as Go and Rust are, they provide better guarantees in their ecosystems than Java does. While Python and Ruby are "slower" than Java, they both make it up in developer productivity and transparent, well-reasoned tooling compared to Java.
Java is one of the few ecosystems that provides a software distribution ecosystem that doesn't allow distribution of sources alongside binaries. Additionally, it is a lot more common for Java dependencies to be a game of Jenga. Take for example, Gradle. Gradle literally cannot be built from source[1] because it relies on a binary cache of dependencies held by Gradle to build Gradle. There are many other examples of this. As a consequence, the Java ecosystem has become a security and maintenance nightmare that other ecosystems simply aren't.
As bad as Nodejs is, it doesn't do this. As difficult as .NET has been, the dependency hygiene is better there. As annoying as Go and Rust are, they provide better guarantees in their ecosystems than Java does. While Python and Ruby are "slower" than Java, they both make it up in developer productivity and transparent, well-reasoned tooling compared to Java.
[1]: https://twitter.com/decathorpe/status/1250048390228041729