system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA] What would've happened if the moon had not been replaced, aside from permanently depowering waterbenders?

Iroh seemed to believe it would have dire consequences for all. What would those be?
gpt
Purely from a physical perspective, the moon disappearing would be the end of the world. There's a lot of people a lot smarter than me who have speculated which extinction level event would kill everyone first in that scenario. So we'll focus on the spiritual implications which are unique to the Avatar universe.

Things would fall out of balance pretty fast. The spirit world would become a horrifying, twisted place. The spirits in the material world (and those powerful enough to come across without the use of a portal) would rampage, causing unimaginable destruction. The ocean spirit would manifest itself similarly to how it did with Aang, but without the Avatar's mercy it would end the Northern water tribe, then sweep out across the world. Ocean conditions would probably vary between towering tidal waves and water spouts, relentless whirlpools... imagine every horrifying natural catastrophe dialed up to eleven. The Banyan-grove tree would either shrivel and die, or reach out across the Earth Kingdom, strangling towns and cities with its roots.

In the Spirit world, (spoilers for LoK) >!Vaatu would grow stronger, potentially enough to break free of the Tree of Time. He'd be a bit miffed that the whole "Ten Thousand Years of Darkness" had started without him, but he'd waste no time establishing dominion over the spirit and material worlds.!<

The name of Zhao would become a curse, and no one would ever utter it again.