Comment by drewbeck
Is your question what’s the positive effect of an unaccountable and violent police force? In general the effect is continued terrorization of poor and black and brown communities and the entrenchment of the police’s municipal power. This is a “positive” effect only to the worst people who want a hierarchical society where they get to be on top by force.
You’re describing a rather far end of the spectrum. I’m thinking of police having sort of a monopoly on violence. And being “too weak” would come with its own challenges.