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

[PawPaw]

But we already know the purpose he served--to point out the weakened celestial currents. Even if a hypothetical replacement isn't as knowledgeable about celestial currents as he is, they can still point she or he in the right direction from the beginning. Of course, someone else might have figured out that the attack was coming from outside the planet, as the four working together did in Elpis. Curious that synergy didn't happen again, huh? Almost like Hermes was sabotaging from the very beginning...

Exactly. The knowledge needed to begin forming a plan of action was already known by Venat and they would have had even more info had Emet-Selch's memories been restored (which from what we have been shown should be entirely possible to do). I still see no reason to use Hermes getting a bit upset as a reasonable excuse for not telling the Convocation what she knew. Would it have been nice to have an "expert" around? Sure. But I have a hard time believing that a workable solution couldn't have been found without him using the information that was already available. Or would have been had it not been kept secret.

[linayar]

I still see no reason to use Hermes getting a bit upset as a reasonable excuse for not telling the Convocation what she knew. Would it have been nice to have an "expert" around? Sure. But I have a hard time believing that a workable solution couldn't have been found without him using the information that was already available. Or would have been had it not been kept secret.

Yes, we could talk about possibilities, but Venat probably did not have that luxury, and when you're dealing with something that most of them hadn't ever dealt with on a scale that could cause a worldwide extinction, she had to make a choice based on the potential risks.