Had no stars? They had more talent than most "stars". Usher couldn't do it without lipsyncing and being out of breath.
The only probably that I found in the show were some of the wigs...
Broadway Shows I've Seen: Hairspray, Chicago, Little Shop of Horrors (2003), The Wedding Singer, Spamalot, Riverdance, Rent, Beauty and the Beast, Spring Awakening, Wicked, Legally Blonde, Phantom of the Opera, Sweet Charity (revival), Drowsy Chaperone, The Lion King, Dreamgirls(2010 Tour).