If you believe in social contagion, then spanking children is a social contagion that leads to abuse

Simple.

You teach people that its okay to hit kids.

You get some people who hit too much and too often, creating abused children who are on their way to become criminals.

To put it simply, its your fault.

Research has long underscored the negative effects of spanking on children's social-emotional development, self-regulation, and cognitive development, but new research shows that spanking alters children's brain response in ways similar to severe maltreatment and increases perception of threats.

https://www.gse.harvard.edu/ideas/usable-knowledge/21/04/effect-spanking-brain#:~:text=Research%20has%20long%20underscored%20the,and%20increases%20perception%20of%20threats.

OBTW, I have a Harvard COOP Card.