Earlier quoted context omitted.
I have helped a computerphobe (hates computers and Internet, clueless, but must use them) with Dropbox. She gets that her folders on various computers around town are synchronized. I had a very difficult time explaining to her that her same folders and files are available via the web interface. Those people are out there.
Most people (as in the majority of the population with access to digital media) have a very difficult time understanding that the filesystem is a hierarchy. I'm always espousing the necessity of backups to my friends/family, which means I've usually got the role of setting up a Dropbox account for someone without a technical background. When I say that their "My Documents" folder is a level above their Dropbox folder…
You are obviously right. But people have been using hierarchies for millennia, e.g. the military ones. Illiterate peasants had no trouble with legion, cohort, centuria, contubernia.
I wonder if the cognitive problem is that the classic file system is an ungraded, unlimited hierarchy - all folders are equal, and you can not find a folders "grade".
Perhaps we would have been better off with an artificial limit of four or six named levels. Instead we're getting the hierarchy removed from general use devices ...
(Leaving aside the "use a hash, not a tree" possibility.)