Libertarianism implies personal responsibility, which implies working for others for selfless reasons. AnCap/Objectivism neuters this important aspect of soceity
Discussion
Couple things-
AnCaps represent a subset of Anarchists
(A small and relatively recent minority of an historically left line of thought)
Objectivists have more in common with (small L) libertarians, but forgoes the "selfless" tortured logic by wrapping it up into one's calculation within rational selfishness.
Last thing.
What is Watts referring to as Anarchist?