I kinda agree; I get that they don't want to change the language definition itself, and by putting things in comments they don't need to do any change in the compiler, but it makes things feel unsafe, or "stringly typed" if you will.

IIRC Java eventually "solved" it by adding annotations as a language feature. I'm not saying Go should add annotations, but just sharing some language history.

And C / C++ has had compiler directives (e.g. #define) since forever, although there too (I believe) # is "just" a comment.