Guitar Hero offers a connection to all this, but departs from it in an obvious way: You're not actually playing the guitar. No matter how good you may get at Guitar Hero, if you decide to take up the real instrument at some point, you'll be starting from scratch.
I don't know what it's like to be a rock star and there's no way I can pick up a guitar right now and play it, but the pretend version of the whole rock n' roll thing that Guitar Hero provides is pretty powerful, at least for this impressionable newbie. Playing Guitar Hero and believing you're a rock star might be like eating apple pie on the internet, but if you don't know the difference in the first place, does it matter?