For example, right now, Li Yao couldn't leave the Tower of the Sun without a professional mentor's proof. If he left on his own, he would be an illegal resident.
The majority of NPCs would ignore you, and the map of the Ancient God World was vast. To travel to other maps, you had to rely on a flying mount or a cargo vehicle.
Of course, every race's capital city had teleportation, but that was something adventurers at this stage simply could not access.
Every key location had checkpoints, and without proof it was a big hassle. You couldn't even unlock basic race reputation.
Without proof, walking all the way to Undercity would be useless, even if it killed you.
"The task is actually quite simple. You just need to deliver this letter to the general, and he'll teach you the power of the Dark Ranger."