The point about the film leader is so the film's sprocket holes don't have to engage both sets of take up teeth at the same time, especially if the film has any curve to it. Engage the lower set of gears with a conventional leader and the top sprocket hole will engage no matter what, but cut the film straight across and sooner or later the top will snag before the bottom is engaged. It isn't a disaster, unless you are trying to load the film quickly.

Steve