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

[CrownySuccubus]

When Emet-selch was like "gg well played" to Venat in Ultima Thule I was actually about to become the Joker. My man, my beautiful fellow, she threw you into a MEAT GRINDER for 12,000 YEARS where you were miserable and lonely and that is all you have to say about it?! You staked your whole life upon an ideal that was doomed to fail because this woman did not trust you with vital information!! I would not be coy with theater speechcraft, the only proper thing to say is "What the hell is wrong with you?!"

Lazy writing, basically.

We weren't supposed to think of that Emet-Selch as the one who committed 12,000 years of atrocities out of despair and loneliness. That was the same Emet-Selch we saw on Elpis with the memories of the one we defeated in ShB injected into his brain without any of the trauma.

Like I said, it's just lazy writing for turn-your-brain-off fanservice.