Brant
Brownlow Medallist
It does make sense.it's not the blunt force impact to the head that matters, the headgear only stops the bruising/bleeding to the impact point. It doesn't help at all when it comes to how much the brain moves inside the skull and its impact with the inner cavity. If that makes sense.....
The brain kinda needs a seat-belt & the skull needs internal airbags. Then, the brain won't rattle around hard, bouncing off the inside of the skull.
As you say, a helmet protects the external (& certainly wouldn't hurt the inside), but it won't stop the internal rattle caused by impact & inertia.