As some of you may know, in the live action adaptation of The Last Airbender, the firebenders now need a source of fire to do their firebending.
They do not create their own fire.
Do note that some masters are capable of creating their own fire, but I don't know their ratios compared to regular soldiers.
Which may lead to some...well...problems.
Last airbender belongs to Nickelodeon, Paramount, Viacom.
Tetris: Trying to get the long, straight block to fit into the space between to other blocks.
Anyway, I felt that this fit more into the flavor of the world.
This is not the case with fire. Putting it out means it's gone forever. It only seems fair that fire should be made as easy to manipulate as the rest of the elements. Besides, fire's main ingredient is oxygen, so it makes sense to be able to summon it anywhere.