yer pitbulls were used to fight other dogs, and animals, so were bulldogs, mastiffs etc. if you really look closely NEARLY every breed of dog was bred to hunt/kill/eat something. you have the origins of the mastiffs (apparently) from ancient rome who were bred to kill and eat PEOPLE in war (and now look at them , then you have all the bullbaiting dogs, the guarding dogs, the herding/guarding dogs who kept flocks together while protecting them from predators, then you had your terriers to chase rats, rabbits, etc etc. you have your gundogs etc etc etc, i could go on forever.
the point is very few dogs are being used for their original purpose these days. VERY FEW. but that doesn't stop people training border collies to not nip at kids ankles, huskies to not run away when off lead (and not pull on lead), terriers to resist the urge to chase EVERYTHING that moves, for rotties to welcome EVERYONE into their home. DOGS ARE SMART, THEY DON'T JUST DO WHAT THEY WERE BRED FOR JUST LIKE TEACHING CHILDREN MANNERS AND HOW TO READ AND WRITE YOU TEACH YOUR DOG MANNERS AND HOW TO BEHAIOUR IN PUBLIC AND PARTS OF OUR LANGUAGE THEY NEED TO NO
...wow sorry, got a little carried away
"In order to really enjoy a dog, one doesn't merely try to train him to be semihuman. The point of it is to open oneself to the possibility of becoming partly a dog." - Edward Hoagland