I think I see Bulloxes point. For the most part our culture breeds dogs for qualities and traits other than fighting, and there are cultures that breeds soley for fighting qualities. Would we still keep breeding if the bragging rights for the best of your breed where no longer there? Love would you breed your dogs if nobody was interested in the traits you are breeding for?
There are places in the world where families breed fighting dogs the same way Love's familly breeds mushing dogs.
That said, breeding for and training dogs for fighting turns my gut. Those on the site that started this thread that defend dog fighting are callous, shallow, and show no love for the dogs they fight, only their own pride as a trainer/breeder.