Actually the quote from the OC Bible is "Thou shalt not build a machine in the image of a human mind. "
You can have calculators and calculation engines it's just mentats were faster.
This element of Dune always felt like an incredibly self-righteous "take that!" to the emerging importance of computer science in the era where the story was written.
Mentats are only superior to computers by act of plot, because mentat abilities start with literally impossible levels of math and memory abilities and push into Thrawn style act-of-plot thinking abilities, and at the high end, outright precognition.
And criticizing a story for "acts of plot" seems incredibly bizarre. Like if your going to read a fictional story without "acts of plot" then read an Apple repair manual.