Because to explain anarchism you have to continually hedge because the system does not work.

That's heirarchy. "a system or organization in which people or groups are ranked one above the other according to status or authority." I didn't miss it, it doesn't matter a union is either self management and yet still utilize a heirarchical structure.

It's relevant because a system that routinely fails in less than a year can't exactly be called a legitimate method of governance. Yes every new government is resisted to some extent, the success of a government against those odds is what determines how effective it actually is.

I imagine you did.

Nope. They say they aren't what you claim them to be, take their word.

: the classification of a group of people according to ability or to economic, social, or professional standing : a graded or ranked series

By either definition there is heirarchy in all but one of your examples and it is in effect a pre industrial society.

Conflict is unlikely to happen without a heirarchical structure.

Arguably yes, in practice rarely if ever.

Then the group leaves, because if the person at the top across in bad faith they people below have the choice of violent revolution or to simply leave same as any other government.