You seem to be trying to elide, or even deny, the contrast between framing and outcomes.When you design a scenario you have already decided to direct players toward that scenario and not something completely different.
My view is that, when we talk about how fiction is established in RPGing, this contrast is absolutely crucial. Without it, we can't talk meaningfully about the contribution to the fiction made by (i) the players declaring actions for their PCs, and (ii) those actions being resolved by application of the action resolution rules.
That's not to say that every RPG draws the distinction everywhere that it might. Indeed, the fact that 5e doesn't draw the distinction when it comes to recovery is what gets the OP of this thread off the ground: 5e players can declare actions whose outcome is that ingame time has passed, their PCs have rested, and so now the GM has to frame a new scene which the players can engage (via their PCs) with full resources. What the OP, together with subsequent posts, points out is that 5e permits the GM to add, as a further outcome of the players' successful action, that the BBEG has been able to regroup and/or marshall resources.
But this feature of 5e is a contingent one. It's not inherent in RPGing. We can see that when we notice RPG systems that draw the framing/outcome distinction even when it comes to recovery: 4e D&D does this implicitly (in my view); Burning Wheel, Cortex+ Heroic, Prince Valiant and 13th Age all do so expressly (though each in a different sort of way).
This is not true in all RPGs. I think even in 5e D&D there are character abilities (eg background features) that make this proposition false.you put the NPCs there to begin with. You have already limited their choice of enemies and allies.
You decided the motivations of the NPCs; if you know your players, you will know which of them thy are likely to oppose, which they're likely to agree with. You decide how to describe the NPCs, their attitude, their behaviours, what they say. You will probably have an idea what the player will find agreeable, and what they will not. You're influencing the players all the time, it is literally impossible to not do that.
I don't think @Campbell is saying that when he GMs he doesn't want to influence play. After all, as a GM he is a participant and not an observer! (Maybe even observers influence play; but participants clearly set out to do so - that's more-or-less what it means to participate.)NPC design including motivations, goals, and what they are currently up to is probably the most significant part of my prep in most games I run. I just consider it part of good scenario design. Once that's set up playing it out with integrity is just part of running the sandbox. It only becomes story advocacy when you start making decisions for those NPCs based on what you think would make for a better story.
He is repudiating a particular sort of influence, namely, "story advocacy" or "story curation" which means (at least as @Campbell uses those phrases) making decisions about what happens next by having regard to desired story outcomes. He has pointed to other ways decisions can be made about what happens next which support him in that repudiation; @chaochou did the same not too far upthread. The range of methods - not all of which any given GM is going to deploy in every game let alone at every moment of adjudication - include relying on the mechanics, drawing upon player contributions and being faithful to one's prep and to the established fiction.
Here's a different approach to NPCs from the one that @Campbell has described, which still allows GM adjudication without story advocacy. I'm quoting Paul Czege:
I frame the character into the middle of conflicts I think will push and pull in ways that are interesting to me and to the player. I keep NPC personalities somewhat unfixed in my mind, allowing me to retroactively justify their behaviors in support of this. And like Scott's "Point A to Point B" model says, the outcome of the scene is not preconceived.
Here is the "Point A to Point B model" that Czege endorses, from earlier in the same thread:
There are two points to a scene - Point A, where the PCs start the scene, and Point B, where they end up. Most games let the players control some aspect of Point A, and then railroad the PCs to point B. Good narrativism will reverse that by letting the GM create a compelling Point A, and let the players dictate what Point B is (ie, there is no Point B prior to the scene beginning).
5e D&D allows the players to control aspects of Point A - hence the whole discussion about what do to when the players establish that their PCs take a long rest. Strongly scene-frame play gives authority over this to the GM. Of course the GM will have regard to what is interesting in choosing point A - as well as the sort of thematic stuff that Czege talks about the GM might also have regard to what will challenge the players in their technical play (this is not a big part of scene framing in Prince Valiant; it is a big part of scene-framing in 4e D&D). But choosing stuff that is thematically interesting is not dictating a story outcome; any more than choosing stuff that is technically interesting is not dictating any particular course of "skilled play".
Of course Czege's approach to NPCs will only work if the system generates obligations on the GM to establish the fiction that retroactively justifies outcomes - systems where I've used Czege's approach quite a bit are in 4e D&D (with skill challenges as the overarching resolution tool) and in Classic Traveller (with its reaction table as the overarching resolution tool). In Burning Wheel and Prince Valiant I use an approach more like the one Campbell describes, because that is a better fit for those systems given their different mechanical features (both have social conflict resolution that works best when it's already established what it is that a NPC wants out of a situation).