A storytelling NPC at a bar would be for those things that maybe should be legendary or at least memorable longer than it takes to drop off chatter, and hopefully should be relevant to the place where the NPC is.
Like, a Snake storyteller at Snake HQ telling the little gangers stories about past exploits. To keep those stories of past ganger PCs going and maybe inspired future storytelling.
A battered sani worker drinking at a bar bragging about all the things they have fought in the sewers.
A VS employee storyteller hanging out in their breakroom, sharing gossip about past events and glories and embarrassments to help teach new hires learn about the history and maybe get inspired on things they can do, too.
The intention being to help make the lore and history breathe in undeniably IC ways that might help new people work out ways of doing things or things to do of their own and keep it going forward. At least, that's how I think of it.
But I see story teller NPC differently from an IC perspective. Afterthoughts is a message from the recorder. With all the noses and ulterior notices that comes with. A story from an NPC might not be any more trustworthy from an IC perspective but those stories might be more that just one person's view.
I could even see interesting uses of both systems. A player had their PC record a message at afterthoughts then the player submitted a story for the story NPCs. And they make sure they don't match entirely.
Will this be used though? I don't know. But I'd enjoy the addition if and of the devs were excited about it.