Libertarianism

Over at the Monkey Cage, they're talking about libertarianism, and it's possible death in the near future.

I don't have much to add on this topic, but as a guy with libertarian tendencies, it has always puzzled me why "libertarianism" is always equated with extremism. I sometimes describe myself as a "moderate libertarian," only half-joking, and people laugh. Why? You can be a moderate Democrat or Republican, but not a moderate libertarian, marxist, or (in the US), a moderate Socialist?

It isn't true that you're either a Marxist or not--there are many different varieties of Marxism, some more radical than others (compare, for example, the mild Marxist tinge of the dependency theorists like Cardoso and Prebisch to the Adolf Hitler grade of insanity of Ariel Guzman and the Shining Path).

Likewise, there are more and less insane versions of libertarianism.

So why does libetarianism need to be an on/off kind of thing. Does libertarianism have to die? Or can it become more moderate?