In a situation where the total amount of resources remained unchanged, the yearly increase in the number of creatures brought about immense troubles for the deities managing the world.
Due to the shortage of resources, famine, rioting, and even war were prone to erupt.
If it were during the period when deities coexisted, such matters would not become a problem that troubled the gods.
With any flimsy excuse for war between the gods, they could easily deplete the excess number of creatures. However, the prospect of the gods having to wage war to reduce an excessive creature population had never occurred in history.
The main reason for the concern over the number of creatures was that times had changed. The beings that dominated everything did not allow the gods to deplete surplus creature populations through the means of war.