Just a yearly reminder that the Xianzhou has committed countless acts of genocides against planets that simply happened to be blessed by Yaoshi. It's not just the denizens of Abundance they fight; innocents have also suffered from their zealotry.
This is addressed in the lore and bits of ingame text, but never in an actual scene, likely because portraying the China expy in a negative light would border on illegality for Hoyoverse. Instead, they are portrayed as heroic to a fault, which contributes to the perception of the Xianzhou as the most boring setting out of every world we've visited.
