Basically, what this guy said:
Yes, because NOBODY had heard of Van Halen, Aerosmith, or Metallica until Guitar Hero came along.
Let's take this logic and actually put it into a conversational format:
"Hello Metallica. We here at Guitar Hero are going to take your recordings and turn them into tracks for our video game. We will then sell those tracks to users (for a profit), and use your music to promote our franchise."
"Oh, and then we're going to send you a bill."