Release groups are also known as Ripping crews, as they will often rip sound or video from the games. Cd protections are often removed as well.
Most, if not all groups are strictly against selling their work. And they release games for evaluation purposes only. So gamers dont have to blow $60 just to see if a game is good.
"Dude, seen that new Al Pacino film?"
"Nah, any scene releases?"
"Yeah, there's a DVD Rip by DiAMOND"