I am mainly saying it is suitable for solving harder problems than Go. Most problems are not hard; Go is good enough for them, and easier to learn and use well.

All these languages are Turing-complete. The difference is in how much work it is to design and write the program, and in whether it can satisfy performance needs.

C++ wins here by being more expressive, making it better able to implement libraries that can be used in all cases. Rust is less capable, but stronger than other mainstream languages.

Sometimes. Better control of performance.

Easier to search for if nothing else.