Indeed, I probably expressed myself quite badly, because I don't think what I meant to say is that outrageous: I heard the opposite, and anecdotally, it seems right - so I would have liked to see the (non-anecdotal) evidence against it. Perhaps I phrased it a bit harshly because what I was responding to was also just an unsubstantiated assertion (or, alternatively, a non-sequitur in that it dropped the "native-like" before fluency).