There is definitely functional bullying. But there’s also dysfunctional bullying.

To take the school example, there’s an intrinsic cruelty from groups of well adjusted kids that is probably useful. Then there’s unfettered abuse from unfortunate kids who are themselves abused, and this is almost certainly dysfunctional and destructive to the system as a whole.

Weeding out the healthy bullying from the pathological is the nuance we actually need.