Why is the infinite ammo cartridge that Nemmy 7 drops banned?

I'm asking for information, because it doesn't seem to make sense to me. This is not a cheat or a code that has to be entered into the game, or any time of modification. This is a legitimate drop that the game lets you use after Nemesis falls. Granted, at that point in the game, it wouldn't save that much time, but again, there appears to be no reason that this item has been banned since it is a naturally occurring drop.

If it was a code or glitch, I wouldn't question it but since it isn't, can someone explain this to me?