I think the idea in the OP is a good one. It's optimistic, maybe too optimistic, though. I think it approaches the bully from a teacher's or adult's point of view (assuming we are talking about kids/adolescents bullying). In that sense, I think it's an excellent approach. Unfortunately, kids being bullied don't hold that position, so they need different tactics.
Adult bullying is requires a different tactics, which I won't go into for the moment.
I experienced some pretty serious bullying as a kid. Most of it was physical. At one point I contemplated some pretty nasty revenge against those kids, but luckily I didn't bring the hammer to school.
When it comes to kids, I think the quicker the problem is recognized and addressed, the better. I guess you could say "DUH" to that comment, but I'm not sure most kids feel comfortable enough or even know how to let someone know they are being bullied.