That whole sudden leap in technology is also stupid when you think back to how Kishi refused to have any sort of firearms created when, in reality, during the age of the samurai and ninja in Japan, early black powder firearms had already been in use throughout the rest of the world for around 100 years, and when they finally started to be taken up by Japan in the late 1800s (where bolt action rifles and the Maxim machine gun were starting to take hold while repeater rifles, revolvers, gatling guns, etc. were the rage), the samurai and ninja were just mowed down, and so even with all the ninja powers, the only ones who would really be able to survive such things in the long-run would be Naruto and Sasuke, and that's ONLY against more basic ones and face-to-face (as a good rifleman could easily take them out with a head or heart shot from a distance and while hidden) or just roll in a bunch of gatling guns, cannons, etc.
So to have such a huge leap in technology and all and yet NOT in methods of fighting (which, even if one or more of the Kages prohibited it, it would NOT stop those interested in it from still doing so, like we saw the scientist guy with the chakra devices) is just completely stupid and it shows that Kishi didn't actually plan/think things out and/or he's just that stupid in thinking that we would actually believe that Naruto could bring about such a thing with "true peace" and crap.
The lack of firearms made sense. One for ascetics its a ninja world not a gunslinger world. Two technology is develop to make life easier, to improve ones lives, or to do something one couldn't do before. It like in fantasy setting why would a mage have a gun when they can just launch dozens of giant fireballs every few seconds.