Every anarchistic community ends up with rules to ensure things run smoothly. I think anarchism should be viewed as the movement towards less rules, not a movement that allows absolutely no rules. Allocating office desks so that everyone knows where their desk is is just common sense - if you're concerned about people envying the best desks, randomise it every week. You have to mark out roads if you want there to be roads.

Law enforcement was probably there because law enforcement said they'd ban the whole event if law enforcement wasn't there. That's how they typically work.