I think this is because modern computers abstract as much of the underlying system away as they can. Smartphones are hiding the concept of the file system under a layer of custom selectors and UI controls to the point of confusion about where files will end up.
Another factor is that (for some mind-boggling reason) it's still acceptable in some office jobs to "not be good at computers" despite working with them 40 hours a week. Whether it's laziness, learned helplessness or something else, people seem to accept that anything beyond the most basic functionality you need for your day job is left for the IT department or techy family members. There's no incentive to even try to learn, even if learning would increase your productivity and make your life much easier, because "computer stuff" is considered too difficult.
On the other hand, a lot more people are using computers today than they did 20 years ago. If you used a computer around the 2000s, you either had an interest in them or your boss had sent you a manual or a training course with instructions on how to use them for your work. Today, almost everyone owns at least one computer, regardless of their training and interest. People are just expected to know how computers work, despite no effort being spent on that in many educational facilities, while content consumption devices get ever more dumbed down.
