That is certainly an interesting analysis of libertarianism. It put me in mind of Locke's notion of government limited to being a "Night Watchman." That does suggest that government must be big enough and strong enough to protect against abuse by the most powerful actors in a society. The advent of capitalism (by which I mean only the mass production of goods and services for sales in geographically extended markets) created actors with power of a whole different magnitude than the 'Enlightenment' thinkers could imagine.