Part of the "problem" is that only big dogs generally cause much damage that is *reported*.
I can't tell you how many times the Napolean complex has shown thru on little dogs. Not all - I've known of many nice 1s. Also known quite a few unstable 1s.
Including the "cock-a-poo" of neighbor-friends I once cared for while they were gone (I was maybe 11 or 12). I sat down while she ate, she came up on my lap, stiff and sort of looking at me, and when I moved a bit - vicious angry growling snap at me. Now this too could be spoiling the dog and not nipping those tendencies in the bud - she died some time later and was never a "problem" per se. But I knew however it came about she was unstable and not totally trust-worthy.