What's the point with that quite lackluster story in Endwalker?

[Nilroreo]

I guess both blessing and echo now protect again tempering (aether corruption). While echo seems more about soul integrity and memory, the blessing give strength boost aside from tempering protection.

I was willing to accept that when Rulakir clarified a few comments later that tempering was an element incorporated into primal summoning only after the sundering. This might've been done in an attempt to retcon Emet's claims of being tempered himself making it easier to just suspend your disbelief and assume both have the ability to protect you... but then Hydaelyn's unending codex entry happened.

Tales of hydaelyn's call and the singular power it was said to bestow-the Echo- have been recorded throughout history. The nature of this power was not wholly understood, and it was often conflated with another of her gifts, the "blessing of light," which ensured one's aether would remain uncorrupted by primal tempering

They address the mix up, then once again single out the blessing as the source of our immunity. Can anyone explain to me why they HAD to be two separate things?

It's particularly disappointing when they had established things like this in the lore with which they could've worked (I don't mean recycling her, just working with the fact that they have this alien being summoned from who knows where, with a very intriguing text description, particularly the bit about the threads of Creation):

Damnit! they blew their Ultima load too early lol!