I don't think government has any business telling parents how to discipline children.
That said, when my kids were growing up I always reserved spankings for the worst possible offenses, like reckless endangerment and outright defiance. And I didn't use weapons---I figured if you feel the need to use something stronger than your hand, you've already lost control of the child AND the situation, and had better go back to the drawing board.
On the other hand, emotional abuse is also deeply scarring.........only the scars are on the inside. There were times when I was a kid that I literally BEGGED my mother to spank me and get it over with---usually about the third hour of her screaming tirades, when she pulled out all the stops in making me absolutely certain I was lower than snail poo. Where was the government back then?
Oh, yeah---it's perfectly legal to beat a child into submission with words. Always has been. Personally, I'd rather see a parent apply a firm palm to the seat of reason.......not only does it deliver the point succinctly, it's less harmful to the child's ego in the long run.