doFiretick makes fire to not extinguish. Lighting makes fire all over the place! That is dangerous, someone can be set on fire!!! doFireTick is console command in game that make fire to not spread, it write like this: "/gamerule doFiretick", but it makes fire to not extinguish natural. In wiki is said that this command only make fire spread on or off, nothing about keeping fire like on Netherrack.