People say that anarchism is useless as a political philosophy: whether you hold it or not isn't going to change anything. Leaving aside the question of whether anarchism is, well, correct, I find it interesting that the charge of uselessness is leveled against anarchism in particular and not, say, socialism or a belief in representative democracy.
Political philosophy is practically descriptive, not prescriptive: it has no power to change the way things are. At its most influential, it might be seized upon as a fig leaf to cover up the machinery of power, like how feminism is used to justify the invasion of poor Muslim countries. Usually, however, the great twin forces of money and violence roll on, forming and shaping our political systems, totally unhindered by the bloviating of philosophers or, god help us, bloggers.