The postulation that bully breeds are harmless to man and beast alike is as broad and unrealistic a philosophy the one that holds them all to be man-eating monsters.
The fact that an average specimen of the pit bull is dog aggressive is OBVIOUS and it rings false when pit lovers try to deny it.
It has also become apparent that there have been more than a stastically meaningless percentage of pti bulls involved in nasty attacks on people.
The fact that so many are beloved doesn't mitigate the fact that their reputation is partially deserved.
Even many pets, whose owners swear up and down that their dogs are totally sweet, carry the tell tale nicks and head scars that are ubiguitous on fighting dogs.
I'm sure many many people manage to have long healthy happy relationships with pit bulls and their dogs never inflict violent damage on other dogs or humans. (I know my old gal Tess - a great dog - never attacked anyone - because she was never ALLOWED to bite man or beast - although she would have loved to sink her teeth in to many dogs and more than a few people).
Personally, I love the breed. But I'd never try to argue that, as a group, they're not aggressive.
Despite the stories that old timers hated people aggression and culled dogs who exhibited that trait- plenty of notorious man-eaters did exist (one example: Bullyson). His genes and the genes of dogs like him course through the veins of thousands of dogs today.