most Anarchist are not against social structures and justified leadership (for example due to experience or in emergency situations).

I strongly believe leadership is not the same as authority. When a precise/urgent need arises, it's only natural to trust more experienced people to deal with it. The anarchist way is usually to organize skill sharing so that these situations where a few people hold the keys happen less and less over time, and to ensure that having the power to deal with a certain situation does not lead to create a form of hierarchy.

It's the old "power" vs "authority" debate :)