Libertarianism sounds fine to normal, prosocial people for a reason: because it only works in a society that is made up of 99% normal, prosocial people. Yes, if everyone was like you and the people you choose to spend time with, it would work fine. But libertarians (big L and, often, lowercase L) are unable to process the fact that we no longer live in such a society. As a result what you end up with is just leftism without any of the teeth required to make a society function.