A 20* swing in body temp would render you dead…

Yep! That's what makes marketing against the imaginary foil of death so impactful: the alternative, "if not for our technical fabric, you'd have to fluctuate between zero and six layers of fabric based on exertion, humidity, inclement weather, and personal thermal comfort", is a lot less manipulative than "wear our fabric or die before the peak". Sure, it's true that you have to wear something or die (unless you're a statistical anomaly, anyways), but marketing based on glove weight doesn't cause as many sales as marketing based on frostbite.

One might expect to be dead if following Modern marketing guidelines.