So I think your 3rd point is highly likely, but I do disagree about the genetic predisposition. If it can’t be genetically influenced then goldens are not more friendly than others, and smart dogs (poodles, Australian shepherd, etc.) are not actually smarter; they all have the same genetic predisposition.

Having an aggressive breed is possible, but as I said earlier I think the 3rd point pushes up the numbers of maulings quite a bit. I’d add a 4th point of a lot of people being real shit dog owners and not knowing how to properly raise a dog to be socially capable without harming others.