Grandma: My computer crashed, I got a new one, but I've forgotten my dropbox password. Dropbox: Okay, can you go get the printout when you registered saying "print this out and never lose it"? Grandma: I didn't print that out / I lost it / the house burned down. Dropbox: Sorry, then you're screwed because we designed our service to be usable only by those who have a deep understanding of computer security.