My take, for what ever it is worth:
The pendulum has to be in the middle, but rarely is.
My Dad never hit us with a belt (or anything else). He always said you hit your kids with an open hand so you know how hard you are hitting them. That does not mean we did not get our hands smacked, we did, but I never felt it was abuse. That, and being sent to your room when you wanted to be playing with your friends outside, were terrible punishments!
In todays world, too many kids are on drugs (to treat ADD, etc) and parents are afraid to discipline their kids. One girl in the neighborhood said in school that "she got hit … real hard". Next thing you know child protective services are at the house, and the parents are afraid to touch the kid, and she is out of control! (Trust me, these parents are not abusive, the older daughter is just a very difficult kid).
There is no "one right answer" for every situation. Some kids need a lot more discipline than others. With them, a lack of discipline does not end well, and you are not doing them any favors by not disciplining them. Society sometimes gets too involved with the "no hit em" rule!
I'll use one of my dogs as an analogy. Lucy (a pit mix rescue) was out of control when we got her, she chased everything with a motor like a lunatic. One day when I opened the gate (to our fenced in backyard) she charged through and went straight for the neighbor cutting his lawn, but luckily just bit the tire on the lawn mower (till he shut it off). I knew if something did not change, she would die. She wanted to charge out of any open door and chase the garbage truck, fuel oil truck etc.
You could hit Lucy with a baseball bat and she would not give a crap, but she is deathly afraid of the water spray bottle. For several months, every time I cut the lawn, I locked Lucy in the backyard with me, got on the riding mower, and sprayed her with the water bottle every time she tried to chase it. IT WORKED! (eventually)
Now, I can let Lucy off the leash even when the neighbor is mowing his lawn, and she does not even try to chase him. I'm pretty sure I saved her life, she was going to get run over by a truck. Sooner or later, a door would open at the wrong time and she would be gone. Not any more!
My point is, you have to determine what may work in each situation, and do it. When that girl in the neighborhood curses at her mother, I would wash her mouth out with soap. That is what would happen to me when I was disrespectful. Her parents are even afraid to do that!