It sounds like mutalism is being straw manned in this thread. I lurk in a lot of anarchist forums and contemporary mutalists do not stress the "common" land right that they are often straw manned for holding. Most just hold a more broad definition of abandonment of land and capital, while most AnCaps hold a 100% absolutist position on land and capital. Yes you will have a few Proudhonoids, not much unlike the Randroid, that call for the abolition of property and and only 'possession' ownership is legitimate but they are the minority. (I have seen one in a board that is 50% mutalist.) The vast majority of mutalists read Kevin Carson and Benjamin Tucker and put less emphasis on Proudhon.
Also just like how Austrian economics are different from state capitalism, socialism in the libertarian sense is different from state socialism. Its definition is worker ownership and operation of the means of production, and there are historical and present day examples of this being every successful.
Also many contemporary mutalists are ex. AnCaps who were tired of Austrian idealism and defending what historically is a corrupted and coercive system.