Really? The only reason?

Only one I can see. Want speed and performance and safety? C++. Want easy multithreading? Go. Rust's only claim to fame is that Mozilla is dogfooding it.

> Want speed and performance and safety? C++.

Speed and performance sure, but safety automatically rules out C++.

> Want easy multithreading? Go

Want speed, performance, safety, and easy multithreading? Rust.

C++ still does multi-threading better than rust, just that go does it better. Similarly go does perf better than rust, just that cpp is even better. So yeah, if you want the worst of all worlds coupled with the pains associated with a brand new language (try compiling rust for a armv5 soc) rust all the way!

Can you show a benchmark where Go outperforms Rust?