As Ken Kocienda describes in his book “Creative Selection”, demos were fundamental to his work at Apple. He and his team used them to highlight the potential, explore the concepts, show the progress, prompt the discussion, and drive the decisions for making our products.
On top of that, every Apple demo review had a decider, the person with the sole authority to approve or not, and the prerogative to declare what would happen next. Demos served as the primary means to turn ideas into software.