Ultra-techy-hyper-fancy materials don't keep moisture from freezing right into them either. Sweat would crystallize into it before it could even be wicked away and escape in such low temps as cold air can't hold very much moisture.
I'm all of a buck sixty and have no problems keeping warm while snowshoeing in just a light shirt and vest when it's below freezing out. If you're just sitting on the sidelines not moving, yeah, you're going to be a lot colder. I'm sure all of the heaters and heated benches made it pretty tolerable, though. I think the QB's and WR's have it the worst since they rely on their hands the most.