I totally agree with this. Any dog, in stressful situations, may bit and show aggression, usually through fear. But the simple fact is that breed characteristics are key. In a freeze, fight or flight situation, certain dogs are only ever going to fight, or attack. They will revert to type and behave in the way their genes and breed heritage would expect them to. No matter how well trained, how well socialised, how well handled by someone who knows what they are doing, a big powerful dog designed to bring down a boar or fight to the death, or guard fearlessly is always going to be a risker choice than say, a soft mouthed retrieving dog, or a little terrier that might well gobby and feisty, but is too small to do any serious harm.
I'll never understand what goes through people's minds when they look at the character traits of a big, strong dog whose breed was developed specifically for bravery, aggression or fighting and say 'yep, that's the perfect dog to bring into my home with two toddlers. Don't worry, I'll train it to make sure it's not aggressive.'
Why not just choose a dog with absolutely no reputation for, or breed history of aggression in the first place? It's not as if there aren't hundreds of other breeds to choose from, is it?