It's a big piece of the learning curve, and one that usually only shows up when you try to write larger programs. Plus there's very little the compiler can do to point you in the right direction when your object soup needs major refactoring. From what I've seen, a lot of folks either give up on Rust or start writing blatantly unsound unsafe code when they hit this.

On the upside, a lot of C++ game programming uses an ECS-style architecture, which does work well in Rust.