That's kind of the joke though right? In 1965, when Dune was written, computer was still a human job title and mentats seemed like a totally reasonable far future extrapolation. Notice in Dune, no AIs, but they did have "family nukes". Really, Dune's vision of the future was about human augmentation through drugs (spice) as opposed to digital automation.

AIs do exist in the Dune world, they were simply forbidden after the Butlerian Jihad. The author didn't extrapolate, he made a deliberate decision to exclude such devices.

Ha, you're right. I forgot about that, but I even read the first book in the series about the butlerian jihad that Frank Herbert's son wrote. I should finish that series... So the thesis was "machines will enslave us but drugs and religion will set us free"? Because, of course, all fiction should reduce to a single sentence thesis, otherwise all those words would be a waste...