Tragic, but don't blame it all on the breed or the breeder
You are correct, it isn't the breed, it is the owner
In my humble, not a DVM opinion, I think it is a complex combination or amalgum of animal breed, personality/temperment, their environment and breeder/owner. In studying human behavior, we face many questions such as which forces in ones self and in one's environment cause certain behaviors. You will hear it as a question of "nature or nurture." Are people born as a blank slate? Do people have proclivities, or inborn tendencies?
I know I am making a leap here, but could we ask the same questions about canine behavior?
Some breeds tend to be associated with more attacks than others. The question is why?
I am going to use a broad brushstroke here, so if you are an exception... but obviously there are people who choose "fighting" dogs for exactly that- reputation. Pits (and other breeds like Rotties) are common among thugs, drug dealers and people who tend to be anti-social and who might be less than experienced at training dogs. Those people, in my experience, do not tend to be responsible owners and probably cause a lot of problems. Does this mean that all of those dogs are somehow bad? I think not. Does this add to the perception? I think so.
To deny that, on average, some breeds tend to have more aggressive members than others seems to me to deny the obvious. But there appears to be significant variety between animals of the same breed and even among littermates. Individual animals within a litter appear to show very distinct and divergent temperments from the moment they open their eyes. Of course some will say that animals don't have "personalities" and that identifying animals as being this or that is a reflection of the observer (kind of like beauty).
I submit to you that, like people, canines are somewhat maleable by their environment; remember Pavlov? But they also have innate tempermental drives. In other words, they are complex organisms which respond to and are formed by both internal and external stimuli. How many people think running from any predator is a good idea?
I have seen people "in the know" mauled by their "properly raised" Doberman and known others who did nothing different and never had any problems.
My favorite canines are actually Canis lupus. Though thought to be the ancesters to all of the domestic dogs, not many people can (or should) raise these wonderful creatures. I have had the opportunity to work with some as well as some hybridized animals and love it. I have studied the pack heirarchy and done a fair amount of research. I always treat the animals with the respect they deserve. I have never had a problem with them (not that they make an acceptable choice for most people). But I have been mauled by "pet" German Shepherds on a couple occassions. Does that mean Dogs are more dangerous than wolves?
I guess i am going on at length, but my point is that I do not think there is a simple answer to this complex question.
Should some breeds be banned or should we treat every dog as an individual entity?
Perhaps there ought to be screening of potential pet owners, ban felons from ownership or training for prospective buyers. But then there is the question of who decides...and who pays and ... big government.
I think, as with firearms, personal responsibility, positive role modeling/peer pressure and individual accountability are key.
Oh, and for canine defense, a .45 ,shot well, is a good round, but a 12 Ga. shot well is much better.
My .02
Shooter429