Because forest fires cause their own weather. Severe thermals taking that heat upwards and drawing fresh air (fuel) in at the surface.
Right. Create their own weather. Which in some cases means lightening storms. So why not drone the fire, and drain those clouds before the electric charge within the cloud builds up to lightening strength? Harness the weather the fire creates. (not that I know a hoot about how thermal dynamics would figure into my brilliant idea) :)