People in cold climate know to always have a full set of outdoor clothes in the car, either wearing them or in a bag even for shorter drives. You don’t want to be the guy who freezes to death after not bothering to put on a jacket since you are only picking up a pizza in the next village 3 miles away and then freezing to death because your car broke down.
Well, the one I bought works damn well for heat and had one huge advantage over wool. I can bungee cord it to my car and be very, very visible to any search going on to find me.
I would hope people going out in winter also have proper coats and pants, but extra blankets as well a proper survival kit is a very good thing. Small grain shovels are also quite nice.
Those blankets have practically zero thermal advantage, and really are only good to deflect wind, rain, and snow. (As well as signaling.)
Please keep a large wool blanket in your vehicle if you are in a location that threatens extreme cold with the inability to walk to safety.
I would hate for someone to be stuck in a tight spot and realize the useless thermal properties of those blankets the hard way.