The entire driveline is offset. It has to be for mechanical engineering reasons. Common offset is 7 degrees. Drivelines components, universal joints, differentials, etc.., that are exactly centered will not last. The work load has to be forced to one side or the other no matter how often the load will change sides. It just can't float in the center or it would chatter and eat itself.
Some of the driveline offset designed into vehicles has to do with the crown in the road too. I don't pretend to understand all I know.