It's just a meme. Some people are into it, some aren't. There are lots of ways to motivate people, and this works for some. I try not to get to wound up over language usage.
I'm just guessing here, but I bet its more about communicating a shared perspective on software development than people thinking they're actually "rock stars". When a job ad says "looking for rock stars to blow a hole in the universe", you would be a fool to take that literally. But its along the lines of a "secret handshake" that lets both parties know something about the other in as few words as possible. A job posting like this is basically saying "hey, we read HN, reddit, etc, we know there's a ton of crap jobs out there full of walking-dead programmers. But this isn't one of them". Of course, the whole "rock star" meme has been hammered to death so that you're more likely to be a company pretending to be something you're not. The point is there is validity in this method of job posting.
It's nonsense.
I recoil every time I see a job description like that. Anyone who believes in those mythical rock star programmers has a serious problem and I certainly don't want to be part of it.
