Using a tablet and pen will allow much more control and versatility in creating strokes than just using a mouse. However, one can use a mouse with similar stroking to produce the outcome. The difference is that to create different-size strokes with the mouse requires changing the size while with the pen it just requires more or less pressure on the tablet. Also, though the other options do create variations in the strokes and painting with the mouse, with the pen the differences are more pronounced.
Thus, as we have said in some other tutorials on the Art Media features, one can have a lot of fun just practicing and going forward in the pursuit of painting in a freehand fashion. The same point is made in using the Colored Pencil. Also, this tutorial primarily uses a pen and tablet rather than the mouse because of the greater control and ability to obtain various and different effects.