The vast majority of non-technical users have no idea you can do this, and I've even heard many say that didn't know you could do it with any site - e.g. they thought they could only do it if the site had a popup that said they could do it.

My mother is 70 and did it on her own once her facebook app killed itself in a botched update (bad install or something). And then she complained that she was using the web version and couldn't find how to do some stuff hehe.

Edit: btw, she's a school/music/languages teacher, so she has very little technical background. In her own words, she "touch[es] everything until it works".

That is awesome, I hope I still have that exploratory attitude when I'm 70.