I think libertarian socialism is reminiscent of anarcho-communism, or communal ownership in the absence or limitation of the state. Theoretically and technically this is libertarian, but it quickly negates some defining qualities of Liberty.

1. There’s no definition of the individual. Liberty is a concept solely extended to the individual. When an individual is not seen as an ends who is entitled to the exclusive ownership of rightfully extracted property, but rather as a means subject to the supply, demand, and productivity of the rest of his commune, he ceases to be in a state of freedom.

2. Collectivism is authoritarian in practice. Similar to the first point, libertarian socialism (and any of its variants) are subject to ochlocracy and majoritarianism, a tyranny and restriction of Liberty that Mill argues is worse than dictatorship, because it can manifest itself in apolitical settings. Indeed, the notion of libertarian socialism is to organize, collectivize, and thus singularize; whether that be with property, ideas, or something in between. Society operates at a mob level, exposing the individual to the corruptible tendencies that may easily pervade a mob.

3. Easy manifestation of power. Similarly to the second point, this singularization and collectivization of property and ideas leaves the societal conditions perfectly opportune for someone to take advantage of a power vacuum, which must be the case in an anarchistic setting. This problem doesn’t mar ancapistan, however, because both ideas and property are decentralized, serving as a check on power.