Typically in stories where ai is outlawed, it's written that way so that it makes sense that people are controlling anything at all (instead of just letting the computer handle it).
The machine isn't evil. It doesn't want to do anything wrong. It doesn't hate humans. It doesn't need to have any particular shapes or design details in the stories. All it needs to have is a singular goal, capabilities, and a disregard for anything else in the universe to be a civilization ending cataclysm.