Or they succeeded, and their goal was just to create a prison for the Yozis. Some demons slipping out here or there? No biggie. But those little cracks make it so no one crack gets big enough for an entire Yozi (blah blah Return of the Scarlet Empress blah). The little branches bend and occasionally snap in the wind so that the tree doesn't blow over. Elasticity over rigidity.

ALSO, as Eldagusto says, the Yozis are at risk of going down with the ship if anything really bad happens to Creation. Even if there were no knock on effect into Hell from whatever apocalypse caused it, which...