Negative situations are a part of life. They make us who we are. Even if we could eliminate bullying entirely, we would also eliminate all of the valuable lessons that a child learns from the experience. This is not to suggest I support bullying at all; you don't learn how to ride a bike without falling, and you don't learn confidence and action without being challenged.
Someone breaks into your house. You're armed. You prevent them from stealing anything. Having mitigated the crime, do you then let the situation drop? Of course not.
Same situation. The homeowner isn't armed. Should they have been? Probably not. If you aren't extremely comfortable with firearms, you shouldn't own them.
But bullying is nowhere nearly as bad as burglary! That's probably true. But the logic is the same. At some point, the situation has escalated to a point where rugged individualism is no longer the answer.
Are there a lot of low-grade situations, particularly on a playground, where escalation to the school board isn't warranted? OF COURSE. That's why we use the term "escalation": there's a spectrum of responses. But in my case, none of those responses involves encouraging physical violence, or tolerating violence of any level directed towards my children.
To press charges, you need to know what's happened, and who's responsible. You may never get this info. I know of people who were viciously bullied, but put on a brave face and never let on to their parents. This kind of situation can go on for years, by which time the lasting damage is done.