So, now a smack on the ass is a questionable parenting ability? Its THE parenting ability known to man that WORKS.
Scumming to your childs misbehaviour is what? A child must have some fear of his/her parents and elders otherwise they will talk back at you, hit others (as is in this case) and maybe in future hit you as well.
Maybe you gave birth to angels, but rest of us give birth to humans and humans by nature need conditioning be it with love or punishment in form of slap on the ass.