Libertarians who are only Libertarian because of the market are missing the point. Communism isn't bad because it fails. It's bad because it deprives people of the products of their labor. Capitalism isn't good because it succeeds. It's good because it respects people's natural rights.

If someone wants to claim that Libertarianism works, (it does) they should claim it only happens to work as a side effect of the fact that it's ethical. Too many people flip it around and try to say that how well a system works is what determines how ethical it is. (It isn't.)