Handicaps in real life are meant to represent a golfer's potential. Handicaps are not meant to merely provide parity and thus are not unfair to the person with the lower handicap.
When people of different abilities or skill levels play using handicaps they are not just playing head-to-head to see who is a better golfer. They already know who the better golfer is. They are actually playing to see who can come closer to reaching his or her potential on that given day.