Well libertarianism could be defined as authority over self, but necessarily applying to everyone, therefore it requires a social contract between individual self-governing agents to establish boundaries. Most libertarians, to my knowledge (and certainly most if not all I've spoken to), are "minarchists" in that they believe there should be a very limited government to govern this social contract by enforcing legal and "natural" rights.
What Zhuangzi espoused was anarchism, which (though some might disagree) is conceptually different from libertarianism.
I'm not sure that it would have been desirable, even 2300 years ago, to live according to "natural spontaneity". Of course, Zhuangzi didn't get to see the benefits of capitalism, the wonders of the internet, etc. It may have made more sense in its historical context, as you suggested.
anagram wrote:
"until then", being either knee-deep in social constructs and institutions (or fighting against them, which isn't entirely different) is inevitable for the vast majority of humans, especially in urban environments. for me, it raises the question: is it possible to have a pragmatic philosophy that effectively limits, in a sustainable way, the influence that formal power structures have on your life? or is some level of active ongoing involvement in politics the only way to prevent even further influence?
I think that being embroiled in social constructs is an emergent property of our evolution as a social animal. Without the tendency to form hierarchical societies, we arguably would not be what we think of as "human". The pragmatic choice would be to take the path of least resistance rather than trying to change the very nature of who and what we are.