Is that even feasible? How exactly would firefighters defend towns from large wildfires. They can't cut an effective fire break around an entire town.
Our house is not fire engineered--but still it has very few spots that could ignite. That's simply because we have stucco walls and a concrete tile roof. There is some exposed wood but not much. Nor are the vents spark proof.
Unfortunately, concrete tile roofs aren't suitable in many places (they don't like hail) and can't be retrofit onto most houses due to the weight.
Even in the case of an emergency firebreak, if there aren't enough firefighters to cut one large one, there aren't enough firefighters to cut lots of small ones with a greater total length.