The question I have is: why on Earth is Go loading a function argument from the stack on x86_64 and RISC-V? Both normally pass the first six or eight function a

The question I have is: why on Earth is Go loading a function argument from the stack on x86_64 and RISC-V? Both normally pass the first six or eight function arguments in registers. Certainly, Go (or any other language) is entitled to use a non-standard ABI for functions used internally, but why use an old fashioned inefficient one?