You are talking about assent to rules. But the location of the pieces in chess is a geometric state of affairs, which can be described independently of the rules for making moves.
I am talking about assent to the fictional position. This is distinct from assent to the rules. I can describe my fictional position without us knowing what the resolution rules are. (
Here's a blog post where Vincent does that, and then works through some implications of this being possible.)
At this point I've read most of anyway, and I recall that post. It describes a process near-identical to the creation of my rules-lite or what could now be called FKR. Albeit I used karma not coin flips. I would encourage others to try play starting from no system. PvP is assumed to be in.
There's these sorts of cases you get to
Someone can just say it (they have control in this recognisable moment)
Multiple people can say it (you need a way to choose, that lets folk recognise when they'll get to choose.. you can see how a karma system emerges from this)
Whoever says X has control (you need to know how to recognise X and you want recognisable moments when X is live)
No one has control (people add to the fiction things they hope will lead to one of the recognisable cases above)
One reason PvP is a good assumption is GM can play with rights very similar to players. They're maintaining world and an extended cast, but when a player says the right thing at the right time that's that. And you want them to sometimes be wrong, so some world and cast things are known from time to time only by GM. (Remember this evolved into a karma system, so no one is wrong just because the die showed 1. In fate systems, GM can disavow hidden information before fate, and take roll to prompt its creation.)
You might recall a few threads back that I made a point out of what above I've characterised here as recognising. I wrote about matching candidate descriptions to norms/rules. That is, identifying fiction as being like F, where F has meaning in our process of play. That's in large part because of this immeasurable quality of fiction. Take Baker's example of "when my kids are present". It's recognisable, right? Consider how Gettier problems might apply though. Is anyone allowed to put in a scene someone who looks like one of their kids, but isn't? It's easy to see that fiction doesn't present us with neatly parameterised cases, so our rules need a way to catch them. Fiction-First PbtA moves do exactly that (when someone says something like this, do this...)
In the sorts of cases Baker describes, what's needed for play is a thumb on the scale. He talks about this... the ur-case is something like
Anyone can introduce conflicting fictions, and background social contracts or status, or aesthetic, rhetorical and other appeals, produces assent (or doesn't, and play falls apart)
This is why I write about goals of game design including alleviating negotiation, because we want the rogue to say "I slip in undetected" and be right.
That anyway blog post you draw attention to is an important one. So much of the rest is built upon it.