Zhong Tian Yun obtained his position as Alliance Leader at the request of the great sects. It was exactly after their loss in the God Realm. It was not even close; they were getting swept out from the God Realm, and the Alliance Leader was killed back then.
He didn't inherit this position directly. The one who inherited the position was the disciple of the previous Alliance Leader who led the war. No one objected to the succession since the disciple was the Alliance Leader's right hand.
There was nothing wrong with the disciple inheriting the position, and they sealed the Sacred Realm, agreeing not to go out to fight the God Realm again. Not that they didn't have confidence in their martial arts, they lost in numbers after learning that the God Realm was a place where people came from hundreds of realms.
