I wonder why they didn't breed sheep dogs to have 40k lbs of bite force? They were actually trained to protect, and they do it admirably.
I guess guys were standing around looking at dogs that actually protect people and herds, and they thought: "shit man, what we should do is breed some moronic imbred dogs with huge stupid jaws into these working dogs. Dogs with erratic behavior and strong prey drives, you know, because our kids aren't being attacked often enough, and now that I think about it, hundreds of years of faithful service really doesn't mean anything when you can get dogs with horrible senses of smell, hearing, eyesight and judgement to watch over out children".
Makes plenty of sense to me.