I'm not sure if it's a myth. Just because we don't know how doesn't mean it's not possible.

It is not easy, but the more domain experience you have through interactions with problems of customers, the increased likelihood of uncovering pain and demand.

On the other hand, trying to create something, and then try to generate demand for it, or find a fit for it is much harder to find product-market fit, because it wasn't started with that in mind.