Kapitel 517: Different Experiences In Other Planes.

Things might be going well in the other planes but the avatars are new celestials that just sprung up from nowhere. That is considered very odd. Everyone is guarded against the avatars in other planes and they are having a tough time blending in. The avatars had to work alone to survive and flourish but they can't match the kind of success that they had in the Zargoth plane. 

Even if the tree father was accepted and worshipped openly without prejudice, there is the problem of the inability to move. It renders the tree father unable to harm the gods of the plane who are in the divine plane.

The tree father received great help in the Zargoth which is why it was able to have such success. Nothing beats the assistance of entities that will do their best to help you for a greater goal. Together, they can achieve greater things than working alone. It is the reason for the existence of Legion and it will continue to blossom as they mature.