Powerful practitioners are usually taught by other experienced practitioners, normally, the people who help others make sure that their student is mature enough, or at least to their standards, know what the heck they're doing first before they get taught.
The large majority if not all, of the experienced practitioners are mature or know how perspective works.
I personally believe in karma, and I don't take action unless someone was innocently lightly injured, even if that happens, unless they are heavily injured, I would just heal up the lightly injured person and let them learn from method number 3.
"By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest." - Confucius
Sometimes, it would be best to let someone go through suffering of their own choice if they choose not to listen to you.