If you think about it, the opening on the air box is kinda small and if you cut it, it will allow for more air to get to the filter. It may not make more air get to the filter, but it will create less resistance because theres a larger area now that its cut. Will this provide more power to the car? Probably not.
If you say the filter sucks air from all sides into the engine, that is true, but it still has to go through that little opening.