I can go into detail, but for the sake of the argument let’s define it in the Norquist fashion: a government small enough that it can be drowned in the bathtub. A stricter definition might be anything beyond and to include minarchism.
I think the argument that minarchists take is that federal law should be modified to only cover military, courts, and police. A coherent libertarian could only interface with those, although it would be difficult and probably start to look very much like the commune types. The Jeffersonian yeoman farmer ideal seems like the clearest example. The larger point is that both extremes seem incompatible with modernity.