Java has over 3 decades of history, during which many IDEs were developed just for Java, and the ecosystem evolved over that long period. Rust is still way too young.

It doesn't have the same kind of high quality tooling, period. People on the internet are not going around saying "look at Rust, such a young language but already has such awesome tooling like cargo, can't wait to see what we are going to have in few years from now". They just simply claim that Rust tooling is superior to anything else.

Because only thing they know are CLI-based workflows for cavemen.