I think gods need a world populated by mortals because they need prayers and souls to sustain themselves. They have to keep making new worlds to survive
Because the power from dead souls don't last forever. All those dead worlds are like dead batteries. If you have 2 live batteries and hel has 3 live batteries, that's 50% more. it doesn't matter than both have thousands of spent batteries.
EDIT: assumign the gods managed to pull the plug on time and save the souls there. if they were eaten by the snarl, then they would not matter anyway