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

[PawPaw]

I've thought that the echo could have been used as well. You could have convinced all of them at that table if they had used the echo to see your past. That seems like a plothole but I don't think Venat, as a third party, could have shown someone else's past to Emet.

She didn't need to show anyone else's past to Emet-Selch. The main thing she needed to show them was the scene in the room where everything was explained and what happened next; which she was very much present for and thus would have known exactly where to take them to tap into the aetherical remnants for viewing the past events. She knew that Emet-Selch and Hythlodaeus had been wandering around with us down below for at least a day so at that point the many researchers that had seen and spoken with us could have helped with advising Emet-Selch and Hythlodaeus on locations they had seen us in together. It's not a plot hole, it's a plot crater.

And they didn't ask to see our memories of Eorzea or the First when we were telling them everything the first time, I doubt they'd need them to be willing to accept the story the second time around.

One of their biggest mistakes of that zone was taking the time to teach us how everyone could use the environment to see past events and then trying to use memory wiping as an effective plot device 30 minutes later.