Fire is actually pretty strong, with the right ninjas. Is he the best main right now, probably not. I would definitely give that to either Earth or water, maybe wind with the right setup. Ninjas like Han and masked man completely shut down lightning mains now. Fire main is actually the most versatile and works with most comps. Could he use some buff, sure. But QOL buffs(quality of life) meaning they give him enough to even the playing field without overtuning him again.

P.S.-I play all mains. But primarily Fire and Earth as of 3.0. In my server lightning mains get dumped on, as well as cross server like space time.