Yep, you do not have children so cannot comment.
Why not exactly? I don't get why people see this as a valid argument... It almost always comes from the people who find nothing wrong with hitting their children too. Perhaps it's because they think the only way to learn about parenting is to have a kid? Perhaps that's why they hit them...
People are against people hitting their partners, but think nothing of them hitting their children. One's an adult in a voluntary relationship and the other is completely defenseless and dependant on the parent... The latter is unquestionably way worse, no?