I think you're saying that because a century ago some people oppressed other people (in America?), therefore free speech was never protected.

If that's what you're saying, I don't see that the conclusion follows from the premise. It is possible for a society to protect free speech in general but to fail to protect it in specific instances. That's a deplorable inconsistency for a society to have, but it doesn't make free speech a "myth". It makes it an inconsistently protected right.

And, if that's what you're saying about 100 years ago, then what is your point about the present? If the idea of free speech is a good thing, then let's make it not "a myth" by supporting it. If the idea of free speech is a bad thing, then let's crush it and silence everyone we disagree with. But what are you saying? How is it being "a myth" relevant?