This critique is limited solely to the modern postwar American version of libertarianism. It doesn’t reference classical anarchism or even modern left-anarchism at all. So it’s focus is pretty narrow. A much more comprehensive treatment of anti-state radicalism is certainly possible. Many of the criticisms offered strike me as shallow and not very well informed of actual libertarian beliefs and the reasons for holding them (and I say this as someone who is very critical of some of the strands of libertarianism described in the article). Still, it’s a rather fair and nuanced article from a mainstream, relatively centrist, somewhat liberal perspective. I take it this writer is not any kind of “conservative” as he fails to get a hair up his ass over libertarian anti-militarism and proposals for decriminalizing things like drugs and commercialized vices.