*watches Pebbles burn all money*
Well guns are limited to magazines in the sense that guns cannot magically reproduce bullets to shoot. Of course it is very easy to kill people with modern technology! But with magic, resources are unlimited, unlike bullets. With guns, you can only shoot as many bullets as you can produce and have with you. Then you have to wait and get more. Magic, on the other hand, is infinite. Even if there was a cool down time, its not nearly as limited as modern weaponry. Regarding Jellal in the first season of Fairy Tail, it took years to build his tower to destroy the world, which is shorter than what it takes to build an atomic bomb, which takes so many more resources. Do you see what I'm getting at? This is not to say that guns aren't dangerous, but you must admit they are much more limited than the infinite power and resources of magic.
What kind of art do you make?