A "good" DJ is one who has a fine collection of records and plays them in a well-thought out entertaining order. There are also performance DJs who use the decks as an instrument.
Both of the above may encourage people to atend a gig or club.
But, why is the fact that the person choosing the records a popstar likely to encourage people? If you needed an elctrician or plumber would you prefer a celebrity or an expert?