Counter point: in the last 40 years I have come off my bike only about 10 times and on 2 of those my helmet was so badly damaged that I think without it my head would have been seriously hurt. Those were both low-speed accidents, one was being hit from behind by a car and the other was hitting a nasty pothole.

I've also seen a friend have a high-speed impact: he was airlifted to hospital, survived and has mostly recovered. Looking at the state of his helmet I have no doubt that he would have died at the scene without it.