Social phenomena as "myths"

It's pretty common to hear things in our field referred to as "myths" in the sense of "stuff that common sense says is real/true, but actually isn't." Some concepts that have been called myths are the native speaker, English as an international language, the idea of "a language" itself, and, most notable to me currently, standard language, specifically "Standard Written English."

This might be really naive, but aren't socially constructed phenomena real, rather than myths, because they're socially constructed? Because the social world is a real world that we live in? Even if almost nobody can conclusively state every single rule of Really Truly True Real Standard English, don't the facts of a million teachers with red pens, a thousand "whoms," and a general vague sense held by almost everyone who has gone to school that there is such a thing as a standard language make it at the very least an important thing to be reckoned with?

I don't think most people would disagree, in fact, that these are "important things to be reckoned with." I just don't think it's very helpful to use the word "myth" to describe them.

I remember when, as an undergraduate, I learned in a sociology class that race was socially constructed. I felt like I had just learned an amazing secret that hardly anybody else had access to. "Race isn't even real," I'd say, as if that somehow settled things. It took me a little while longer to realize what real meant.