If we understand anarchy to be a condition of existence without the state, without (semi-)permanent institutions of hierarchy and domination, then we can say that it is the most successful evolutionary adaptation of humans; for 99% of our history as a species, there was no state and no such institutions.
Throughout various human cultures, community cohesion is maintained through different means of decision making and implementation, some of them resembling what we might call "consensus" and others not so much. Regardless of what some anarchists might prefer, these models are only incidentally (definitionally) anarchist, since they are unconscious, rather than deliberately chosen for philosophical and/or socio-economic and/or socio-political reasons.
The problem for anarchists in general is figuring out whether we want anarchy or anarchism. Anarchism is a European political philosophy whose adherents and supporters offer it as a program for organizing a future society (with prefigurative tools and methods, blah blah). The goal is to abolish the state and capitalism, which can be understood not only as authoritarian -- but as aberrant -- social institutions. In order to succeed, anarchism would seem to require a vast majority of humanity to become anarchists, while anarchy doesn't really require anyone to be an anarchist.
Getting back to your question about consensus then, my answer would be "no." Sharing certain principles in common with a dozen friends doesn't even mean that consensus is possible or necessarily desirable. Consensus can look an awful lot like enforced conformity or totalitarianism, especially to someone with a different opinion from the majority. Anarchists usually include the idea of secession from any organization/federation, and that indicates a reluctance to fetishize consensus.
