Out with the old outdated style and in with the new. I think if you lose patience with your kid so badly that all you think about is hitting them for your own selfish needs of releasing your own frustration (making yourself feel better, thinking only of yourself at that moment), you suck. The parent isn't the one crying even more, nor feeling pain, they're not the one scared, they're not the only pleading to stop.
I believe you can have boundaries and parent without relying on objects to ''teach'' a child.