The idea is to prevent the small fire from getting to the tank, and poping that safety valve
That makes sense... but by the time it's to the tank it's probably pretty big... we live in the woods and most tanks are surrounded by trees, shrub, etc.
We are required to keep a clearing around the tank / above it... but IMHO it's not nearly enough to prevent it from over heating and popping the valve and tossing flames.