>>102810412GOLB directly created a creature akin to the Lich (its entire body was billowing the same death-breath that the Lich commonly uses), with said entity being both capable of assimilation and similar corruption, whilst also being fucking invincible. That alone would kill all life. And we know that GOLB can directly cause things to cease, as with Margles and the Pillow-World, so there's that to consider if you manage to somehow beat the lesser demons.
GOLB would quite clearly cause the end of everything if left unchecked.
