To prevent the traffic loss.
When the traffic comes to FuseClick,it can’t execute the offer under following 3 circumstances:
(1)   The offer is in Invalid status (Paused, Archived or Expired).
(2)   The offer has reached the caps limit.
(3)   The enforce GEO targeting option is ON and set the GEO countries or device is ON, but doesn’t set any redirect offer.
 
So, if the Backup offer is set, the traffic will redirect to the backup offer. If the affiliate didn't set backup offer, the traffic will redirect to the secondary offer which admin has set. And if the admin didn't set secondary offer, the traffic will redirect to the Network Global Redirect URL.If the admin doesn’t set the Network Global Redirect URL, then the traffic will redirect to Error page.