It shows the maturity of the sport of MMA compared to boxing. When a boxer loses in the octagon, no one in boxing really gets riled up about it and realizes that they are different sports anyhow (before and after the fight), despite the gloating of mma fans as their sport is supposedly better. But when a boxer does win in the UFC (like Holm over Rousey), boxing fans give respect to their martial art of the sweet science without going overboard and saying that MMA is dead because someone who previously boxed won in a cage.
They are different sports and they don't have to be in competition - Boxing is boxing, MMA is NOT street fighting, a street fight is a street fight - MMA fans need to get out of the ideology and terminology of referring to their sport as being the closest thing to a street fight. Street fights are barbaric and immature and anything can happen. MMA is what it stands for, Mixed Martial Arts; give it respect as being that and not the disrespect of a back alley fight.
A combat sport is sadism with structure and that is art. Fighting outside of that is disgusting, and typically bullying. Self defense is needed in the outside world, but even that is a cruel act of nature as it is reflective of people fighting out of basic survival, not because they want to. Defending oneself in a sport is an art on display of two men who want to fight, exemplifying literature of the heart being written with fists and blood.