Umm, no, the 70-year-old crippled man would be protected by the community's voluntary association devoted to stopping crime (crime being the limitation of another's freedom, such as the 5 men with guns threatening the old man). Why does having a community organization for protecting people against such displays of authority necessitate a centralized, hierarchical social system? It doesn't, and if you'll look at the histories of Spain and the Ukraine you'll find the proof. As I have already explained, anarchy does NOT mean every man for himself. It means that those organizations necessary for the public good would be organized according to the principles of direct democracy, egalitarianism, free association and mutual aid.

What I mean by self-defense is the ability for the community to defend itself against violent, anti-social people. It does not mean every person is solely responsible for their own protection.