It's not about pacifism. The Mormons are my example expressly because they weren't pacifist, and they got rolled by a national military. The point is that unless you've got some kind of world wide vibe going someone is always going to amass enough power to overcome whatever mutual aid defense you can setup. And you would in fact be creating a state.

States don't have to be highly centralized bureaucracies. It's literally just a term for a geographical area that works together under a specific governing regime. If you're calling the banners for mutual defense then you're fulfilling a key aspect of a state. A nation is a group of people. Nation State is a specific category of states that happens to cover most countries in the past 100 years. For example although the US is a nation state, anthropologists have identified 12 sub cultures that could be considered nations of their own, largely linked to major immigration waves.

Now that we've got that out of the way, if you somehow get a world wide agreement to abolish centralized government, and tame the corporations, and then prevent the mega cities from becoming city states, how do you prevent Communes 1 through 10 deciding they want to band together and start forcing other communes to join them? That's going to require the other communes to band together for defense, which is going to require pooling resources, which just recreates the international MIC at a smaller scale. The problem with anarchism of any kind is shitty people look at it and all they see is a power vacuum, and a comfortable life in power if they have the ambition to take it.