> A much better tactic, and one that I see neglected far too often is to instill the reasoning into the kids from a young age, don't bar them from what's bad from them, teach them that why and how it's bad so they themselves keep a distance.

That can work - until they fall in with a bad friend, once that happens they lose their ability to self regulate (the bad friend does it for them instead), and the parent must do it for them.

So as long as you are lucky enough that you kids never fall in with the wrong group you will have success.