>>33446846 (OP)
Eben if you don't accept nihilism or moral relativism, evil can be done in service of good. That's what most medicine is. Invasive surgery to fix something. Taking small doses of poison to correct and imbalance. Asserting independence from caring parents. Retaliation when someone crosses a boundary.
Experiencing evil is also nessesary to mature. "I can survive evil". Knowing intellectualy is different from first hand experience. I admit evil isn't usually done to cause maturity, but it's one of the benefits.