"Anything to the effect of "we want rockstar developers" suggests...that they consider most of the applicants that they get to be of low-quality"

Yep. I'm cool with that. I like working at places with high standards, and I'm glad they understand the difference between good people and great people.

I'm an infrastructure guy (who happens to program), and I've worked with people who are both competant and people who are great. Both can do the job, but working with the latter makes a world of difference to both the work environment and the output.