Anarcho communism rejects ALL forms of hierarchy. It's quite environmentalist and some argue that it's a precursor to an "advanced primitivism." Any economic system based on wage labor and private property requires a coercive state apparatus to enforce property rights and to maintain the unequal economic relationships that inevitably arise from differences in wages or amount of property. An 'anarcho' capitalist society would inevitably divide labor into classes after assigning artificial numerical values to someone's work in attempt to regulate production. Anarcho communism advocates the equal, horizontal structure of organization over the oppressive, capitalistic and hierarchical structure. Many mistake this for collectivism (like Marxism) -- it is neither individualist nor collectivist. The market is replaced with a gift economy where everything is for free -- distributed either by a general surplus after production has passed the need to consume or by free stores. How can one 'afford' to give things away for free? By the ability to receive for free! Viva liberty, viva equality.
And what happens if civilisation is attacked by indestructible mutant 7-foot mosquitos? Does it account for that?