That's exactly how this works: it doesn't have an impact, except when you ask it to. This is an idiomatic approach to this problem.

The part I object to is overloading comments, which aren't meant to be load bearing. A tool developed outside the language has no choice but to take something that has no meaning and overload it, but language owners weren't forced to take this route; they could've made directives not comments.

In practice, the Go language developers carved syntax out of comments, so that a comment is "anything that starts with //, unless the next characters are go:"