Physical punishment is not a type of punishment that can easily get out of hand.
People who lack self control and discipline can easily get out of hand, whatever method they use.
You ever see how army interrogators can mess a person up completely without physical means. Messing their minds up in ways that will never heal.
That may be the extreme of mental and emotional punishment, but look at how many completely messed up kids there are out there because their mind has been scrambled with mental and emotional punishment over time.
Different extremes of any punishment will bring different effects.
Physical punishment can go to the extremes of serious physical, mental and emotional harm or death, and this can happen quickly, in a matter of seconds.
Mental and emotional punishment can go to the extremes of serious mental, emotional and physical harm or death. Although the physical harm or death sometimes goes guilt free because it is often by the hand of the mentally and emotionally abused, and can easily be "separated" from the abuser.
Some people might look at how quickly physical punishment can get out of hand and consider it a disadvantage when compared to mental and emotional punishment, and it is true that it is a disadvantage. But the quickness of cause and effect with physical punishment can also be an advantage.
And while the extended time it takes for mental and emotional punishment to do damage can be seen as an advantage, it can also be a disadvantage. In the case of physical punishment, for people with average self control, when they spank the child, they will immediately see the reaction from the child and if they spank a little too hard one time, the reaction from the child will show them that they spanked too hard, so the feedback is immediate.
Mental and emotional punishment is more complicated, especially as the child gets older, it can escalate slowly over time without being noticed, and if the child doesn't express how they feel (which is often the case with abused children), then the parent might not even realize the effect, until enough damage is done for it to show and by that time there could be a lot of damage, either hard to repair or unrepairable. Some parents if they had known the effect, they would have stopped, but since they didn't notice, it continued.
The Discipline with no disadvantage and only advantage is teaching the Right. And not just telling the Right, but teaching the Right so the child Iverstands the Right.
If teaching the Right doesn't work for a parent in a particular instance and they feel the need to punish, then the most important thing for the parent to learn (no matter what kind of punishment) is Self Control, Self Discipline and Observation.
Haile Selassie I