Because secondary effects are impossible to untangle or verify. Maybe IAV is just a made up term that people use, or far more people believe that they have IAV

Because secondary effects are impossible to untangle or verify. Maybe IAV is just a made up term that people use, or far more people believe that they have IAV than is actually the case, or that they are wrongly convinced that IAV is incurable or untreatable, or the medical system has been perversely incentivized to encourage medically assisted suicide in the case of IAV diagnosis, or it's actually the case that it's not IAV causing the agony but actually a prescription drug side effect that interacts with the brain in such a way as to invoke IAV in certain cases, etc etc. None of that is science, of course. Separately, there should be a list of rationalizations for victims that undergo medically assisted suicide. And it should be analyzed to find ways to reduce the number of suicides.