Only angels or demi-gods could be pure libertarians. The rest of us have to settle for something less. The libertarian point of view dictates that person A can do whatever he/she wants, provided that action does not infringe on the rights of persons B-Z to do whatever each of them wants.
Libertarians point out that the founding fathers were essentially libertarians, and that their philosophy is in our country's DNA. We didn't want the government of England to tell us what to do. OK. No federal government, or one so limited that it can barely keep a small navy at sea. For that matter, libertarians think we should have little if any state, county, or local government. Fine. So do I. I also think the season should always be early autumn, we should be able to retire at 22 and live on our own country estates with thoroughbred horses.
Unfortunately, most of us don't have the luxury of critcizing the human anthill from an ivory tower. People could afford to think like this when (if ever) we all lived in small villages, and each of us lived by taking care of a tiny farm. We breathed the same air, drank the same water, relied on the same rain to grow our food, and worked together as best we could to help those hit by disaster.
Each of us provided our own security, food, medical care (such as it was), sewage processing, transportation (walking), old-age pension, childcare, and education (such as it was). As long as God provided the right amounts of rain and sunshine, things were tolerable. Each of would have had to go out of his or her own way to interfere with anyone else's right to do whatever he/she wanted to do. This was, and can be, the only environment in which libertarianism can exist.
Let me add here that much of the world still lives in this kind of environment, such as it is. Small villages where people practice semi-sustainable agriculture in an attempt to keep from starving. Unfortunately, all of the farm land with rich soil and plenty of rain and sunshine has been paved over and/or is controlled by wealthy non-farmers. Too bad. That means most of the world has to survive on the edge of starvation, or find a non-agricultural job. That means everything complicated. So complicated, in fact, that libertarianism is pragmatically useless.
The second I go off the farm to herd sheep and cattle, I potentially hurt others by using up the grass and leaving the land open to erosion. I could end up contaminating the water others drink. However, if my herding provides enough benefit, i.e. I slaughter enough animals every year to make it easier for everyone effected by my negative impact to get thorough the winter, maybe it all balances out. Maybe. But who decides if it balances? Everyone has to vote on it, and then someone has to enforce it... wait a minute, now we have government. Our Libertarian index just dropped by 10%. (Yes, this is the tragedy of the commons)
Next, some people will (justifiably) make the argument that they suffer more than others due to the effects of animals getting herded around, and/or do not get benefits equal to what others do from the slaughtered animals. Now the government we created will have to take from some and give to others in an attempt to make it fair. Otherwise, they will get voted out of power, and someone else who seems more fair minded will take over. Woah. Now our index has dropped another 20 percent. We are only 70% libertarian, and civilization has barely even started.
Of course, in a properly disabled post-apocalyptic world, libertarians could flourish in the tiny survivalist communities.