I mean, the filesystem is just hierarchical organization. It's not even really a computer skill - I remember being taught how to use an encyclopedia in school

I mean, the filesystem is just hierarchical organization. It's not even really a computer skill - I remember being taught how to use an encyclopedia in school with its index. The UI is not a big deal because graphically, there are only so many ways to represent a hierarchy. Even 3d file managers are pretty intuitive because the base data structure is simple. It's really easy to use a computer when someone has already programmed it to do the things you want. It's much harder to use one as a machine that can be programmed to do anything.