I agree that there is typically a "superstar", but it's rarely the ones that believe they are a superstar. Often times the so-called "superstar adds so much abstraction and complexity to a product that it feels only they can deal with it, because the rest of the team can't and does not want to deal with it. Work piles up and moves very slowly and it feels the "superstar" is the only one who does the job. Then superstar burns out, quits and leaves the "mediocre" team to deal with the mess.

For me a "superstar" is a friendly capable coder, who simplifies, teaches and learns in a feedback loop. They are indeed very rare.