Right now they're not a main power. The main powers are those who hurt people and cause incidents. Madara, for instance. When those happen, the residents work together to solve problems.

But the people like Madara don't work with others like them to cause more chaos. They have their own ambitions and no reason to work together, no goal.

Destroying the police force could become that goal. They're making themselves targets. And if Madara and a few others worked together it would be very difficult to stop them.