In C/C++, dependency management is not as convenient as in Rust. There's Conan, but you have to install it. Rust comes with Cargo.

So, in C++, there are more game engines developed using a minimal amount of dependencies, and in Rust, there are more game engines developed using more external dependencies.

As the majority of people transition to Rust, even the people working on "lower level" code will also forget what internals are about.