Scoop your point is absolutely right. When I lived at my mum's, the guy next door got two rotweiler puppies. He was a big spose you could say " tatoo sporting skinheaded grock", but nevertheless a really nice man, had lived there years. Of course he get's two rotties and the stereotype comes to frutition.
Anyway whilst the dog's were young, he spent a lot of time on the front garden with them during the summer, when kids would walk past he would let them stroke the dog's, keeping an eye on the behaviour of the dogs at all times.
He let his young nephews spend a lot of time with the dogs on the front, always being with them at all times.
Anyway to cut a long story short, the dogs are lovely animal's now and as soft as anything when it comes to the public.
The guy quite rightly says he would never trust the dogs with a stranger or child unsupervised, but I think it pretty much proves your point that a dog is brought up to be violent.
I think he got the dogs for the love of them, whereas a lot of owner's who get them type of dogs, do so to defend their owners and premises and then train them up to violent and vicious.
Maybe there should be an attempt at more control of dog owners??
I suppose at the end of the day though, EVERY dog has a vicious nature if wound up the wrong way. And I suppose, like with many human's, it only takes one little thing to set them off??