Speel, kids need discipline. There are times when parents or teachers need to employ more drastic methods of enforcing discipline, and in a way they are failing in their ability to enforce discipline by resorting to such methods, but sometimes kids need to at least be threatened.
If a (troublemaker) kid knows that a parent or teacher can't enforce discipline, then they'll run amok.
Of course allowing parents and teachers to use more drastic methods of discipline will mean that the system will be abused. No system is perfect. But having a system is better than no system.
IIRC, my parents have never hit me, but I was threatened with it enough times (IMO, justly so), and the threat (and the belief/surety that they would carry out the threat if provoked) was enough to stop me acting like a little ******* !
When I was in primary school I remember a kid getting his mouth washed out with soap :-)
There are problems with where to draw the line, but IMO it is absolutely necessary to give parents/teachers the authority/responsibility to threaten and carry out more drastic forms of punishment. It is dangerous to say things like "as long as there are no lasting marks" as there are some horrendous forms of punishment/pain/torture that leave no marks, including mental abuse.