At one point I was stationed at a military base in the north which got to -40, even -50 somewhat regularly in the winter. Part of the orders for extreme cold was "no bicycles". Too many cardio nuts were seen riding in inadequate clothing, especially lack of proper boots. The worry wasn't them getting cold, it was them falling.

A light jacket is all good when you are pumping out the calories, but take a fall and you are now sitting on the ground unable to move. At -40 you may have only minutes before life-altering cold injuries (lost toes). Add to that the darkness and snowbanks and you might not be found for hours... IF anyone is actually looking for you. Cellphone screen get tricky in serious cold. A person walking to work, which was still not advisable, would at least be wearing clothing warm enough to stand still in the cold.

The radio used to have public service announcements calling for people to keep blankets in their car. Not in the trunk. Within reach of the driver. Get into a wreck, trapped without heat, and that fleece blanket under your seat might save your life.