I feel you, but there are limits.
think of wolves. when the pup gets out of line, the alpha or whatever will bite the pup's neck and throw him down, and maybe scrap for a bit. this teaches discipline, and this is how society should work as well.
kids get too mean and don't know their limits. a poppa wolf will not injure the younger wolf, it won't make it bleed, and it won't beat it beyond recognition. some kids do that emotionally.
there is a difference between being taught how to hold your own, and being taught that you're not worth holding your own.
same shit goes for parents hitting their kids. obviously parent's shouldn't be striking their kids, but some kids are so fucked up and out of line they deserve a solid belting. my sister is one of those kids, she's publicly throwing scenes all the time (at age fucking 13) like on the show supernanny, and my parents just don't know what to do with her so they enable her. she's going to make for one fucked up young adult after highschool.