[Kuroshima]

Well, in my campaigns, up to now, gunpowder is like crack cocaine to fire elementals (and so do most chemical explosives), and that's the main reason for the Ban. Sure, you can have gunpowder, but sooner or later, a fire elemental will find your stash, and it won't be pretty. On top of that, there will be fire elementals that will come to see you to destroy your gunpowder stashes to prevent other elementals from becoming adicted...