In spite of assurances to the contrary, I have never once seen libertarianism/abolitionism/voluntaryism/anarchism fail when used in the real world.
Yes, people frequently fail to use it, but that's their failure. It rests nowhere else.
Libertarianism is a tool. It's always the right tool for the job when you're talking of human interaction-- among individuals or societies. Yes, there are other tools you can use-- none of them are as good and all of which are harmful to individuals.