Code that has an Arc<Mutex<>> around every single type in Rust could be made a lot better. Code that does the same in Java could not, because Java doesn't have the ability to make types not wrapped in Arc<Mutex<>>. If you wrote perfect code in Java, it would be equivalent to Arc<Mutex<>> code in Rust - which is not hard to write at all, presenting minimal annoyance. Lest I be lambasted for comparing to a JIT language, that's also how everyone writes C++ these days, and for the same reasons.
But that's not how anyone looks at code. They see the ability to unbox types. They see the ability to borrow instead of moving. They see the ability to modify stuff in place instead of making it immutable and then deep-copying it. In most cases the code to do so is shorter and easier. In some other cases, it's longer and more difficult. And people exclusively look at the latter cases, the fact that it's difficult to further improve past what they previously thought of as perfection, and declare Rust to be Hard™, and go back to Java where they can attain perfect code, even if it's worse than the Rust equivalent.
Like nerd-sniping, except you do it to yourself.