Over several pages RonJ has patiently explained the function, use and need for the drift-nut in increasingly basic terms, and still Action80 doesn't seem to get it.
How about this? You can use the drift-nut, or you can work it out in your head, or you can use pencil and paper, or an I-phone. What you can't do is ignore it. One way or another, if you want to travel further than grandma's house, you need to compensate for something on your directional gyro.
Its there, its real; now what do you suppose that something is?