No one in the whole movie ever asks anyone, Did you write this letter' Part of the reason is that no one wants to hear that it isn't for them. As soon as they read it, they want it to be theirs.
“David Lee Roth had the idea that if you covered a successful song, you were half way home. C'mon - Van Halen doing 'Dancing in the Streets'? It was stupid. I started feeling like I would rather bomb playing my own songs than be successful playing someone else's music.”