The pope is not a tin-pot dictator. He is the Servant of the Servants of God, which means that his role is to serve the faithful. To toss anyone out of the Church, merely as a raw display of power, would not be service. As for the extent of his power, even the pope is bound to follow canon law and to respect the structures that are in place for the protection of individual Christians. He may change disciplinary law if there is compelling and just reason to do so, but he may not simply ignore the law. He is, as I believe Pope Benedict XVI pointed out, the guardian of tradition, not its master.
