The issue is that it expliciely says that it's not manageable. It says "the ecosystem can't support this".
The ecosystem of a Hell presumably bears little resemblance to that of Earth.
Especially since its not just mundane biology.
But magic as well.
And as has been pointed out, Earth itself is supposed to require change for Humanity to survive.
This does not mean that everything is horrific and doomed to die. It means things have to change.
Which is very much in theme with Molly's coming.
If Watchful Bane's domain is destroyed, it dies. If it gets killed by a spiritkiller, it will die.
A potential Chicago god would bear much the same limits at a minimum.
Not like this. Not all plot hooks are good, and this is one of the bad ones. You keep telling me "the juice isn't worth the squeeze". I am telling you here - it's not worth it at all.
I strongly disagree.
Incentivizing Molly to go out and fix things for her new kingdom is good plot, and it provides plot points on which to hang a bunch of other things, like the Hell's Loyalty status and the Lord of the Land point.
City Gods as a concept yes. Exalted style gods forged with Infernal power, no.
For one thing, those gods need mantles to interact with the material world. Based on the example of the previous god we made, our's don't.
That's a categorical and fundamental change.
One, what made them doesnt matter.
A god under this cosmology is still a god, whether made by Infernal crafting or a necromantic Ascension ritual.
Iku Turso's example suggests we wont be seen as something unheard of. Rare sure, but not unheard of.
Two, gods requiring mantles to interact with the mortal world in a divine manner is new.
As far as we recall, the gods withdrawing, or being made to withdraw was just about a thousand years ago, circa Hastings.
There's wizards that were alive back then, let alone other sorts of supernaturals.
Many of those gods are walking the earth now in their personal capacity; we've seen a maenad of Dionysus in the series, and Thor is supposed to be off in professional wrestling.