Both, mass production gives the ability to resupply, rearm and attack again. While it it obvious that the ninjas do have jutsus and summons but you forget if they rely on chakra too much they will exaust themselves while using a gun all you have to do is reload. Therefore mass production makes the bullets almost everlasting. I dont know the if the villages use factories or if they are still into blacksmithing and etc.... Also just the power of a nucleur(not sure how to spell) weapons alone could raise any village and the fact that these weapons can be launched from miles away unlike jutsus where you have to be relatively close completly overwhelms the ninjas and their technology!!!

P.S. to let you all know I am not dissing the series I enjoy It very much except the filler episodes.