How small of a group do you imagine? City? District of a city? We already have these structures in place and they ultimately produce the current environment. Cities want someone to dispute their conflicts which leads to counties and states and the federal level.

There is not a nation state in the world that is not centrally governed. The world has q already optimized for this structure. You always need someone to settle disputes without resorting to violence, and this dispute resolution just goes up the ladder, eventually escalating in war.

Id like to see an example of self governance in the real world or even an imagined one that takes into consideration the current state of the world.