Remember how in a sidequest in Shadowbringer it was established that it may be possibke to save the 13th?

Like they litterly make us send a porxy filled with ather into the void to find out if travle would be possible and rebalancing of the 13 ather an option... And the answer was yes... And we never ever did anything with that knowledge.

Entering the 13th in the aim to save what is possible would have been precisly the clean slate I imagin the story would have needet after Endwalker. But it not even getting mentioned ever again feels very disappointing.