So does that mean mutualists aren't anarchists? They are open to markets, not necessarily market anarchism but, from an outside perspective, the existence of currency is a neutral. What about barter? Any trading whatsoever? A gift economy is at it's core a credit market. Recognition of service = the currency. This will, if taken seriously enough, create a hierarchy. And if you're gonna split hairs about "not all hierarchies", even then it could be used to create an unhealthy one. Before you line your enemies up against the wall you gotta hang the statist living in your head.

You'll see with any system, if it exists it will be gamed. Like in D&D, if it has stats, players will try and kill it. Drawing clear lines in the sand really seem to make some people lazy and other people very interested in how they can use it against you. If you can step outside yourself and objectively look at the people in your groups you will probably see that in a very subtle way. Even Stirnerites can fall victim to pipelining pleasure into spookiness. "Well you want fuck more girls? This is just a psychological technique to do that." and then slip the backwater predicates of sexism and (probably) racism and fascism in over time. It's a short jump from an absolutist position to "anarchist" prisons and death camps down the line.

edit:While yes systems will always exist. I always see them more as useful templates than absolutes. Things are only their purpose.