A 1st grader hit my wife's vice principal in the head with a chair last year.
Now, as for punishment, how would you punish a 7 year old whose dad is in jail, mom does drugs and deserted them, grandma, who they live with, is a POS and the kid is better off, and safer, at school. Because the idea of "punishing kids like that is an almost daily occurrence at my wife's elementary school.
Kid breaks the rules, gets violent, does something to someone, but NEEDS to be in school because their home life is s***. My wife and her administration deal with this daily. They have to balance between keeping the other kids safe and getting a good education and not letting the kid who needs to be in school to even have a chance at life stay at home where they will get abused or ignored.
So, yes, it's a bit mote complicated than "Suspend them and let the parent fix the problem". The parents don't fix it, or can't fix it, or don't see that there's a problem.