I'll provide a simple application of personality types that is probably relevant to a lot of people on this board.

I think that people who have trouble learning a computer task may have a multitude of different reasons for it, not just a position on one end of an MBTI axis. I see that your choice of step-by-step instructional style worked for teaching your mom, but a step-by-step instructional style works well for a lot of people. Most people, in fact.

(I happen to work at a company that writes computer training, so I've got a lot of real-world experience to back this up.)

By saying that "MBTI told me she was an S, and I changed my teaching style to step-by-step, therefore MBTI is useful", you're simply showing confirmation bias via a testimonial. There's nothing scientific or testable to back up your claim that the N/S axis is the reason that she responded well to a step-by-step teaching style.