Non-economic reasons for anarchists to reject libertarians

It's a punishing fanatical dogma for libertarians to defend the free speech rights of everybody. But no Anarchist ever has to defend the human and civil rights of any known Fascist. " Fascism is not to be debated. It is to be smashed " - Ben Durruti See also Agonism (from Greek ἀγών agon, "struggle") that is a political and social theory that emphasizes the potentially positive aspects of certain forms of conflict. It accepts a permanent place for such conflict in the political space. Tl/dr there are non-economic reasons why anarchists violently reject such offensively stupid ideas from the lunar-right as libertarianism. PS - I assume anyone not living under a rock knows anarcho-capitalism is an oxymoronic non-sequitur