if parents taught their kids to defend themselves from bullies there might be far less bullies in the world. the one thing a bully does not like is someone standing their ground no matter the outcome. "beating" a child to prevent them from doing this is akin to taking their belongings away to teach them stealing is wrong. it's a very mixed message to send a child especially since a child's mind is not developed like an adult's mind and doesn't really comprehend what you're trying to teach them by doing that.
my mom was a "violence is never right, even to defend yourself" kind of parent and THAT type of parent is worse than a parent oblivious to what their child does. it basically teaches the child to tolerate bullying and never do anything about it. that enables a bully more than anything else. bully does A to get response B from victim. when victim gives response X the bully is confounded by this and over time learns that bullying isnt all it's cracked up to be. especially if one of their victims defends themselves and puts them on the ground.
as a buddhist i abhor violence but i also recognize, based on my own experiences, that there are times you cannot avoid it. i dont start fights but i am very willing to finish one though i prefer to not get violent at all.
i have also found that bullies tend to come from broken homes and dysfunctional families though this is not a hard and fast rule. so beating that kind of child is only going to make things worse since the child is acting out based on how they're being treated at home, they're taking their unhappiness out on others to make themselves feel better or to feel some kind of control over another person as that's what their parent is probably doing to them. it's cyclic in nature as most dysfunctional behavior tends to be. broken homes produce broken children who grow up to have broken homes of their own.
i do recognize nobody is literally (i hope not anyway) encouraging parents to beat their child but physical discipline can be a detriment. i've seen what family life at home can do to people based on my own friends growing up as a child and it's extremely sad. i was abused but some of my friends were abused way more.
spankings are not a cure all to these problems but learning how to be a better parent by learning to say no and teaching the child the right values in life can go along way to prevent the child from needing the belt to begin with. the problem stems from poor parenting or a lack of parenting period. the child is merely a piece of clay, whether that clay turns into a beautiful vase or an ashtray is up to you. i think society is being too intrusive into how people parent their own children though their should be some measure of encouragement from society to help parents be better parents.