Walker had taken a great deal of time to speak to each and every single demon that had woken up. His conclusion was that there was more to this than he understood. The world had the rules that every race had believed as true for all they could remember. That after a certain age gaining a system is impossible. However, there were demons who were being given another chance here if they helped to complete a major chain quest that would free their people.
On top of all this, there was the fact that besides the will of the world, there was a demon lord who had sent a general to attack the humans just to weaken them. They had completely abandoned the demon general Pride and their army as soon as the job was done and now the kingdom had lost almost all of its' harvest for the year.