I feel like the actual discussion in that thread was about the primary GM role that new gamemasters should focus on learning: scene-framing for player agency or literary performance. The whole conversational vs. literary narration bit was a red herring conversation that we unwittingly got roped into when literary performance camp asked us to conceive of GMing as a conversation without the literary performance. We could and did, but that was still not good enough, and so here we are.This was the division that existed in the thread in question. Not saying it has to be one or the other.
That said, I tend to view most roleplaying as a constant state of negotiating the fiction. This is generally done conversationally between GM and players with mechanics often serving the function of a mediator of narrative outcome resolution. Sure, narrative prose can potentially add to the immersion of the game, but it is a non-causal relationship, so I regard it as a secondary concern when compared to the importance of scene-framing for players and as a player. What ultimately matters, IMHO, is that players understand what the GM is trying to communicate, the stakes of the scene, and how they can engage the fiction.