SneerClub

(No spoiler tags because it's just background lore for Dune that's very tangential to the main plot)

Dune - after catastrophic wars between humans and AIs, computers are forbidden.

That's a retcon from the incredibly shit Dune-quel books from like 15 years after the original author had died. The first Dune was written well before computers as we know them would come in vogue, and the Butlerian Jihad was meant to be a sweeping cultural revolution against the stranglehold that automated decision-making had achieved over society, fought not against off-brand terminators but the entrenched elites that monopolized access to the setting's equivalent to AI.

The inciting incident semi-canonically (via the Dune Encyclopedia) I think was some sort of robo-nurse casually euthanizing Serena Butler's newborn baby, because of some algorithmic verdict that keeping it alive didn't square with optimal utilitarian calculus.

tl;dr: The Butlerian Jihad originally seemed to be way more about against-the-walling the altmans and the nadellas and undoing the societal damage done by the proliferation of sfba rationalism, than it was about fighting epic battles against AI controlled mechs.