The diagram is showing the ball flight laws if the body alignment, feet, hips and shoulders are square to the target line. I understand you can aim in different directions. If you aim 10 yards to the right of your target you would be better off hitting a pull draw then a push draw, it all depends on what shot you are comfortable with.
norrisedgar, The statement in bold is not correct, the dotted line is the target line/body alignment. It does not mean it is the start direct of the ball. The black arrow is the start direction and the red arrow is the path/swing direction.
The ball flight laws in the diagram are relative to the target line. If you have a hard time swinging with an outward path to hit a push draw then you can aim lets say 10 yards to the right of the target line, swing along your body alignment and hit a small pull draw to get it back to the target line. Like Erik said there are many ways to get it done.