It is stupid. Parents will just buy the lighters for kids, and they'll use them anyways. If they don't use lighters, they will use matches. If they can't get matches, they'll use something else. Besides, I had lighters, matches, and all sorts of things to set things on fire and I never smoked, cause any major damage, or kill anyone
Now, if you wanted to ban kids from having lighters/matches/whatever from school then I'd be totally fine with that, as they don't need one there.