I think she is right. You can complain about a kid's behaviour all you want but don't assume you know the answers.
I never assumed I had all the answers. But if your kid has no self-discipline and no manners then you failed. If your kid is a whiny
**** you failed. If your kid becomes a Donald Trump or a Paul Bernardo then you failed.
And contrary to her opinion, the harshest judgement of kids behaviour are parents who have well-behaved kids. Because they look at that and think there's no way in hell their kid would get away with acting like that.
Now I understand the difference of opinion between parenting methods involving hitting and not hitting. But clearly, from this kid's shocked response, hitting was a new experience. So I would suggest whatever other method was being used failed.