here you are proving one of the things in the article. helmets are risk-enablers, despite not providing the protection they are assumed to have.
some facts: the ASTM F2040 helmet standard: flat steel anvil at 22.3 kph, which corresponds to a theoretical drop of two metres, the impact on a hemispherical anvil is at 17.3 kph, and the impact on an edge anvil is at 16.2 kph. rotational acceleration is not considered or measured.
keeping in mind the above figures, the average maximum speed seen by 650 consecutive skiers and snowboarders at 3 different resorts on wide, groomed, blue-square trails is 44 kph or more. these trails are the sort of trails where the most fatalities occur. skilled young adult male skiers and snowboarders tend to go even faster than the rest of the population. this group is also the most commonly fatally injured.