Why should parents be or not be allowed to hit their children?
Do you like it when someone hits you? Probably not and you probably would retaliate and hit that person back. Now you have two angry people who want to fight. Have you solved anything? No! You’ve just created new problems.
The same thing happens an adult hits a child. The child probably wouldn’t hit the adult back. Instead, they will find a smaller child to attack. Congratulations, you just created a bully.