It does change all the time, and dictionaries don't ensure any kind of standard. The linguists who write dictionaries will tell you that their only function is to describe the most popular parts of the language, not to prescribe any particular rules. Telling people how they should speak doesn't actually work.

I could say the phrase "abso-fucking-lutely" and you understand it, even though it's not in the dictionary. That's still language, it's still English.

And I don't know what you mean by a "'hard' contradiction" or why that matters. My point is that both language and gender are forms of communication that rely on socially constructed signifiers and they are both fluid to a similar degree, so the analogy is good. If you want to argue with me, that's the point you should be dealing with.