An idea about collaboration passing by

Ya know what was I thinking? A D&D based collaboration where one person would be a narrator leading protagonist through his own (narrator's) world and the other would be a protagonist exploring and doing stuff. My guess is that it would be fun way to explore other people's imagined worlds 'cause you could go around, ask whatever you're interested in, travel the world and meet different races and cultures and stuff assuming you won't get yourself killed in the middle of the story. You could just wake up one day as with amnesia knowing shit about yourself and the narrator could lead you through story and tell you about your race (assuming you picked to be one of narrator's made up races).
I would like to hear your opinions on this kind of collaboration. Would it work? Would it actually be useful to you?