Yeah but only because Rust (and arguably Zig) didn't exist when those compilers and operating systems were written.
C++ is the industry standard for existing software but it would be dubious at best to start a new project in C++. Especially something that has essentially no dependencies like a compiler. GUIs and games, sure.
Believing that all new software should be written in Rust rather than C++, and that this situation is inevitable anyway, is one of the core tenets of this church.
Obviously you shouldn't start any project in any language because you have no idea what you're talking about. Spitting myths and folklore stripped of context is not what engineers do.
C++ is the industry standard for existing software but it would be dubious at best to start a new project in C++. Especially something that has essentially no dependencies like a compiler. GUIs and games, sure.