Bullying is what happens when an individual with power exercises that power against people who don't fit in. By threatening to expose or harm or degrade the outlier, the bully reinforces the status quo in a way that increases his power. [Physical bullying is a different phenomenon... I'm mostly writing here about emotional bullying.]
"I will punish you because you don't fit in, and I will continue to punish you until you do."
Bullying persists when bureaucracies and hierarchies permit it to continue. It's easier to keep order in an environment where bullying can thrive (and vice versa), because the very things that permit a few to control the rest also permit bullies to do their work. The bully uses the organization's desire for conformity to his own ends.