I have a friend who is in his 70s who is otherwise quite competent but he cannot comprehend the fact that the Finder represents a tree. Some nodes (files and applications) are leaves; others (folders) are not. That's on him. The other thing he has trouble with is that Save and Open dialog boxes in applications present a different view of the tree than the Finder does. That's on Apple for not defaulting the Save and Open dialogs to the last window you opened in the Finder, and vice-versa.

The upshot is that he can never find anything on his computer, and if I'm not around he just drags everything to the desktop, because at least there he can find it.

My guess is people don't organise their folders well and then struggle to navigate and search properly. Which shouldn't mean the rest should get punished, but here we are.