...of course nothing is the individual dogs fault in the sense that the dog is morally culpable or responsible...but that is because we are talking about a dog, and not a human. But, a pit bull is a pit bull. Take my "disgusting dog" as a critique of the breed if you want, although as you point out, there are exceptions which are not representative of the breed, but that only reinforces the point about the breed.
I'm absolutely sure there is a nurture (or lack of nurture) factor to it, thus my inclusion of the dog owner as being disgusting, likely for raising a mean dog...and also for selecting a mean dog breed for living in close quarters with families. It is irresponsible and disgusting. That breed is more likely to attack children; I don't get why anyone would choose to invite such an animal into their home.