My understanding is that this is a hypothesis that has generated a serious revolution in linguistics, establishing linguistics as a science, just as Newton established physics as a science.
But it has not been confirmed any more than in the 18th-c action at a distance had been confirmed. Linguists are still working on it and will continue so for some time. Wild counter-hypotheses by bbright non-linguists are mere static -- but linguistics itself may, or may not, undermine this hypothesis.
But when that hypothesis by some analogy is carried outside linguistics, and used (for example) to maintain that different conceptins of "Justice" share a deep strucutre in the human brain, we have left systematic thought rather far behind, and seem merely to be thrashing around for a way to onfirm a long-standing ideological assumption that damng it, some things are good and some things arent, and everyone past present and future has to know that.
Carrol