Norm aren't the same thing as policy. Norms in a community get created by conflicts being resolved. It feels to me that there are conflicts where we currently lack an effective way to resolve them.
Having an institution like enwiki's arbcom that can bring a conflict to a resolution would be valuable.
Yeah I think your observation is right. We don't have good processes/institutions/... to resolve conflicts. I only have experience with a group like you mention in a group outside Wikimedia and the result is so-so. What are people's experiences in Wikimedia?
We on nlwiki have an AtbCom as well; unfortunately they are necessary as judges are necessary in the real world. Sometimes they make contraproductive decisions tlike blocking people from subjects, name spaces etc