Well if people didn't illegally copy games, we wouldn' need it would we? It tends to be the small minority who spoil things for everyone else.
You'll always have pirates. It doesn't really matter whether there's DRM or not for those who want to pirate. They should be trying to make it easier for people who want to pay for games to be able to do so. Why spend millions, hundreds of millions on coming up with DRM technologies when people will crack them in no time?
Valve have got it right, piracy is a service issue not a security issue.