After reading definitions and asking for clarifications elsewhere, I'm to this day having a hard time getting an unambiguous understanding of what things are covered by the term Borgstromancy, and which ones fall outside of it. I know that people usually describe it as using rules (or, sometimes, other literal statements that people are prone to read metaphorically when they aren't) to convey unusual or unexpected truths about the state of affairs relating to the setting or campaign.
For example, Exalted1 has a magical ability (Charm) that gives one an automatic success at a search for food (no buts, no ifs listed), which is a way of conveying that the Lawmakers are so awesome that they can find food (not make, not summon, find) even in the empty vacuum of space in a few hours of searching to feed themselves and their followers.
The above would seem clear enough on its own, if not for the fact that it turns out the term is not that simple: there seem to be many things which would seem to fall under the above umbrella but aren't included.
For example1, the way the rules make it possible for the same groups to have different combat efficiency depending on whether they are fighting a party-level skirmish, or an organised mass combat, as well as the ability to apply some Charms to one's unit, is not considered to be an example of Borgstromancy, but rather of rules not acting the way they should, even though elsewhere the lore hints that the laws of logistics and strategy are different in this setting just like the laws of physics are (some classify it as the Cargo Cult of Borgstromancy instead of the real thing).
What makes the first example a good example of Borgstromancy and the second not? What properties make some rule be or not be Borgstromantic?
1 I'm leaning towards Exalted examples because that's the ones I'm familiar with. I'm just as interested in examples from or explanations related to other games (Chuubo, Nobilis or even non-Moran games!), though I'd probably be slower to understand them if I'm not acquainted with them.
What are rulebooks for?
They're for people who already know the rules and setting, to remind themselves.
If you want a foundational principle of Borgstromancy, you're not going to get it from Dr. Jenna Moran, who is lifestyling this hard and will say she writes "to make as many people happy as she can", to quote her own intrusion into a thread on this topic.
So here's my take: she writes as though you already understand.
Text With The Borgstromancy Nature
As though you understand what it is to be a creature which defines itself in relation to, and opposition to, ideas of reality; it does not "exist" so much as it "is not like the thing which does not exist". As though you understand what it is to take a dodgeball to the head, attain enlightenment, and transfigure one of your classmates into a form suitable for fighting the monstrosity which has inexplicably appeared to threaten the peace of the city and also their heart.
This means it's rather light on explanations in what a first-timer might feel would be the proper time and place for such things. People who already understand don't constantly talk about the fundamental principles of what they're doing, after all. What is this, a pulp sci-fi novel?
But it means that you can bounce extremely and unexpectedly hard off of anything she's written, in a manner not seen since the first man glued foam onto a ping-pong paddle. Though it also means that, if you can hold on long enough or get help in order to understand what's happening, everything falls into place, and the rulebook can do what you use it for, which is to remind you of the rules and setting you already know.
So, for a simple example: in first edition, Sidereal Exalted can manipulate fate. One way they can do this is that if an encounter "is starting" (a minute of freeform socializing or two combat rounds) and it seems like this is a horrible trap only a stupid person would fall into, they can not be a stupid person and declare they were never there, and then they weren't.
This tended to run into problems when Terribly Offensive Shogun (not an actual character name) wanted to know exactly where the Sidereal had run off to so he could use Carrion Crow Reaps Creation (not an actual power, probably) to go there and punch them, because of course he wanted to punch them because they were right there talking to Master Merchant Bao, except they weren't because they were never there and AUGH!
This text has the Borgstromancy nature, and so there is something you can understand to make it make sense: a Sidereal doesn't think in straight lines, or have an answer for "how" that would satisfy anyone who does, so the relevant bits of the power are the only bits you need to know. They spend the points, and then they were never there, and things proceed accordingly.
Similarly for the example of foraging for food in space: this is a cosmology of myth, and space is not a vacuum but, for instance, a sea of stars, in which it is of course possible to catch a fish!
Text Which Lacks The Borgstromancy Nature
There are, of course, other sorts of rules you do not understand and for different reasons; for example, second edition Exalted turned Sidereal powers into a giant pile of illusions and teleports that might potentially have interlocked better with Terribly Offensive Shogun's terrible offensive schticks, but were in parts complicated and unclear.
This text lacks the Borgstromancy nature, because there is nothing you can understand which will make it clear. This can be for the regular boring human reasons: that rules can be complicated and ensuring they will mesh is hard, or that rules are written by different people at different times and compiled by still different people, or that any error can be overlooked an arbitrary number of times.
Or it can be for less boring and possibly worse reasons: someone who wanted to pretend there was something more complicated wrote as though there was something to be understood, using allusion or Capitalization, Implied Significant and figuring someone would fill in the blanks later.
Combat at different unit scales is likely to be the first case. There is no deep secret here, just confusion.
But it's always hard to be sure.
Discerning A Text's Borgstomancy Nature
Borgstromancy is a bit of a paradoxical term to apply; you can't rely on your initial experience of the text to do it. Obviously it's something you have trouble understanding in the first pass, but without a word from the designer or help from someone who already understands (including Future You, after some research) you can't tell if there's something underneath it.