I agree norms are a distraction. It's about incentives. Every group/organization has an incentive to look strong to outsiders. It therefore minimizes internal conflict because that makes it weak. It most importantly minimizes visible conflict because it makes it _look_ weak.

However, every group/organization is just a collection of its members who each have different incentives. For some of those, it's gaining status/power. Status/power is mostly a zero-sum game, therefore gaining it requires attacking others (causing conflict). But causing visible conflict is damaging to the group so other members are likely to punish such behavior. As a result, the optimal strategy is to cause conduct conflict invisibly.

Bullying is nothing more than such a parasitic individual trying to achieve status/power or in some cases simply satisfaction.