The definition you choose to use is one-dimensional and superficial in the face of an ample showing made that the word is charged with meaning. Your own adherence to "myth as falsehood" itself perpetuates a myth, does it not? I think your purpose would be better served by saying what you mean in the first place; rather than trying to shoehorn a definition that is not necessarily apt.
Once you get past the need to defend your position, don't you really mean "falsehoods" or "lies"?
Now, if you and some others wish to get into a pissing context over what the word myth actually means, its up to you, but its a red herring which has nothing to do with the casual premise of this thread.
I have not put forward a hypothesis by posting this thread, and I'm going to stick with the meaning of the word myth as i understand it, even though it will make me come across as simple-minded.