Perfect example to compare to is Vampire Hunter D. Vampires, Demons, all sorts of fun stuff from the 'old times' but yet weapons like crossbows and swords are still used. Along with guns and such, but it's just a fictional creation designed to give a conglomeration of many different aspects to please the viewer. Watching somebody blow away 30 vamps with a big gun is pretty damn fun. But seeing a normal civilian in Naruto pull out an Uzi and drop 10 Jounins or something...That's just stupid. ...Right?