having an elite QB is the best way to be able to win a superbowl, no question about it.
however, not all teams have the luxury of a Manning, Brady, Brees, or Rodgers. at that point, its more important to have stronger players at skill positions such as RB, WR, and TE as it can help out average QBs an awful lot, and still give you a chance to compete for a superbowl, as evidenced by decent, but certainly not elite QBs such as Brad Johnson, Trent Dilfer, Eli Manning, and Ben Worthlessburger winning Superbowls.
so I won't say that RBs or WRs are neccesarily overrated, they just aren't nearly as neccesary if you have the luxury of a great QB.