One disturbing thing I see is parents entertaining their ASD kids with computers/tablets/game systems. Sure it keeps the kid out of trouble but you are doing what we call “Feeding the Beast”. High impact stimulation on a brain that is already firing a mile a minute anyway. You can lock me in a dark closet for hours and I can still entertain myself. My brother did it all the time.
My saving grace was that I was a voracious reader, which was a good low-impact brain exercise.
Unmanaged access without design or purpose may be as you say, but there are good examples of devices like iPads, used with certain and specific “apps” designed for kids on the spectrum - do produce good results.
One of the things that we’re considering is an app that gives a close-up and visual picture (video) of words, so that our child can study it over and over, for word formation. I’ve noticed that he studies the lips very closely with certain words. There have been good results from this kind of app.