I'm sure if anyone digs deep enough, they can find an example of either experiencing or witnessing and being affected by abuse.
I was never abused physically or sexually, I was not mentally manipulated or yelled at. I think I only ever got one spanking, and I freaked out and told my mom never to do that again, and she felt so guilty that she didn't. One time, the neighbour kid's mom smacked him and her hand went wide and she ended up getting me a bit too. I ran home and told my mom, and she marched over there and gave that neighbour lady royal shit. I had friends who had to fetch the leather belt for their dad whenever they were caught misbehaving, and even then I couldn't fathom the horror of the idea.
My parents did swear a lot, some would call that abusive. They yelled and screamed at each other when I was home. I didn't like it, and some people would call that abuse even though it wasn't directed at me. But if Child & Family services took away every kid whose parents yelled at each other, well there would be a lot more overloaded group homes and foster parents than there already are.
Incidentally, besides people relating abuse victims to non-monogamy, they also relate it a lot to BDSM. I know in the anecdotal evidence I've collected, a lot of the masochists I've personally met were in fact given corporal punishment as children.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker