Turning over the earth is an absolute essential duty. You need to turn over the dirt to plant your seeds, but also to increase soil gases, as roots require access to carbon dioxide, the gas that is the primary required gas for plant metabolism. So tilling provides aeration for root structures and sets the stage for planting.
Plows turn over the topsoil, while they create a natural fertilizer from dead plant materials. These are the plants killed by plowing. Plowing also removes weeds.
Anyone who wishes to cultivate should turn the earth. You can do it with a shovel by hand, or you can call Compy's to do it for you.