Drain the battery, can't start the engine, still stuck, no more heater (for the typical, unprepared motorist). I doubt any motorist stuck on the Beltway without heat would die of exposure, but still, it's conceivable for people to be stuck a long time, and you might not be stuck with other motorists to help you. If you may be stuck for a while, it would be good to have some idea how well the recommended advice from the TV/radio works, including how long your battery can last doing that, if in fact you are draining it over time.

The James Kim incident might be an example of a situation where that kind of information helps a stuck, unprepared motorist stretch out how long they have some heat, given their fuel supply and battery charge.

Actually, the emergency flashers is a good point. Way back in high school, I remember draining my dad's car battery just sitting outside a girl's house chatting with her with just the emergency flashers on and the radio on for quite a while. I was shocked, maybe the battery was near the end of its life. Her father was not happy to have to jump start my car in the wee hours of the night. And that was a summer night. I imagine a car battery in the dead of winter would be a lot weaker.