The problem is not with the sport aspect of combat arts, per se, but rather when the sport aspect becomes the driver of the direction of the art.  This usually happens when, in order to gain popularity, the powers that be try to steer an art into the realm of sport. Usually this requires that the safety of participants increase, and that the art become more spectator friendly.  As such, rules are set in place without regard for whether the art remains realistic (i.e., how many times have you witnessed a street fight go to the ground, only to thirty seconds later of inactivity have a third party bystander stand up the two fighters?)