"That level of cold can destroy a lead acid battery".

In cold winter with heaters, lights and wipers on, if you travel mostly short trips, you are drawing more out of a battery than you are putting back. Batteries have lsee available power when the temperature goes down. If your battery is low, it can freeze up. That I uderstand.

But, how does a block heater help with any of those (for todays gasoline cars)? Maybe a battery warmer would help? But, either only help when you start your car at your house.

As to fuel economy, a car warms up fairly fast, so the fuel saving from a block heater is marginal.You are using some electricity, I suspect.

So, what's the benefit of pluging a gasoline car, (not diesel) in at home in the winter? Could it be a Crysler thing?