Actually the facebook login case was one of people using computers using a limited skillset(ie using search bar for everything), not necessarily being stupid. Well, that plus being impatient.
On a personal note: my mother in law used to only use browsers history (down arrow) to access her sites. Since she only uses about 10 sites this worked very well for her.
One day, she was very upset, when my browsing on her computer "broke" her computer.
She is not stupid, and once I showed her how to set up shortcuts on toolbar, her computer was "fixed".
I wanted to write a longer reply, but this article covers it pretty well: http://www.osnews.com/story/22884/The_Facebook_Login_Thing_B...
On a personal note: my mother in law used to only use browsers history (down arrow) to access her sites. Since she only uses about 10 sites this worked very well for her. One day, she was very upset, when my browsing on her computer "broke" her computer. She is not stupid, and once I showed her how to set up shortcuts on toolbar, her computer was "fixed".