According to Osho, the state has not disappeared because the world is still not communist; as long as capitalism persists anywhere, the state and dictatorship remain. More crucially, Marx ignored human psychology: personal egos, national rivalries, and the corrupting grip of interim rulers on power. Those in power don’t relinquish it, so classlessness, borderless unity, and the withering away of the state never arrive.
Because the whole world isn’t communist and leaders’ egos won’t let them give up power.