The problem of power accumulation and anarchism...

Libertarians seem to underestimate the coersive effects of concentrated privately held power, while some of those in the many manifold concept known as the "left," underestimate the coersive effect of power held in the name of the common good. In what way can power safely be accumulated without it turning into a corrupt image of it's original, perhaps noble, intent; especially considering today's means of control(ie. television, propaganda, advertising, planned obsolesence) of individual agents? I know Anarcho-syndicalism advocates the democratic control of work places and the federated association of these, but doesn't this federation entail a risk of corruption as power is accumulated. Also, those who subscribe to anarcho-primitivism advocate much more decentralized localized groupings of power, but doesn't this lead to similar problems that indigenous populations face when encountering groups, such as 'western civ', who have power concentrated in the hands of a few? How can modern technologies ensure that power is always only ever put in the hands of actors who will ensure the collective good? Can Anarchism be described as any set of tactics which opposes unjustified power accumulation?