Hierarchy is not an accumulation of power, but authority vested in individuals. Democratically accountable, there isn't anything inherently wrong with it.
Additionally, inequality is not an enemy of Communism. Communism is about providing for everyone and giving everyone a dignified life, not about making everyone equal. "From each according to his ability, to each according to his needs" inherently accepts inequality of circumstances and outcomes as acceptable as long as everyone's needs are met, which is impossible in the contradiction of Capitalism.