I don't believe in physical punishment, but there is a grey area for me.
One - my sister and I used to fight a lot. Nothing serious, and we gave as good as we got. Young humans are not massively different from young animals, so it seems counter-intuitive to me to expect them to understand that hitting is wrong especially early. It also, in the vast majority of cases, doesn't result in violent adults.
My attitude to physical altercations is vastly different to my husband's though - he sees tickling me or poking me as legitimate teasing, but gets very upset if I get frustrated that he won't stop and smack him on the wrist to bat him away when he reaches for me.
The difference, as far as I see it, is that he had a much younger brother, who he would tickle and tease, but of course never hit as he understood the power imbalance being 12 years older.
I had a slightly older sister who I quickly caught up with in size. Neither of us would stand for tickling or poking without physically defending ourselves. A slap or a scratch was par for the course if you were stupid enough to push it too far.
He sees my batting him away as 'violent', but I could never STAND that sort of pokey, tickly horseplay from adults, whereas I didn't mind clouting my sister and being clouted back.
Two - I may change my mind on this when I have kids, but I think when the lesson is a physical one, a physical warning might be the most appropriate. E.g. - a child messing around reaching for a hot plate when they've been warned not to. A) a smack on the wrist might be the only way to stop them in time, in the same way you wouldn't worry about lightly bruising a child to get them out of the way of a moving car and B) it's a taster of the physical pain they would have otherwise suffered much worse if you hadn't intervened.
I'm not sure it's easy to replicate the lesson of 'hot = pain' without a bit of firsthand experience.