True, but one of the little things many people don't realize is that in order to allow the house/attic to breathe we have these louver vent thingies under our eaves.

Air is sucked into the attic through the louver's and exhausts though other vents. During a fire, all it takes is one ember to get sucked up through the louver and it doesn't matter what you have for roofing material. The fire starts under your roof.