the second quote in there relates to american football helmets....."Helmets and other devices have been shown to reduce the risk of severe head and facial injury, but current designs appear to make little difference to rates of concussion."
So which would you rather have? A fractured skull or a concussion?
I was recently in a pretty bad car accident. My worst injury was a mild concussion from whacking my head against the head rest and a cracked rib from being restrained by the seat belt. So, in relation to your argument, I would have been better off with no seatbelt and no head rest. In which case, I would have been either impaled against the steering column or had my neck broken by whiplash.