Ratskinner
Adventurer
We've discussed this before. I still don't think I follow. Why does rules proliferation push towards G or S? If the rules aren't simulationist in orientation, you can avoid S. Why must they push towards G, though? Because they create a framework that can be exploited, thereby allowing gamism to emerge as the "creeping doom"?
Yes, to some extent. I don't really think G or S has to be "creeping doom" at least maybe not "doom". (I think some of that is Mr. Edwards' own proclivities coming through, or my take on his proclivities.

...bear with me and I'll try to explain my thinking as best I can....
Narrativism, heck story, really doesn't need much. You just need enough to set up/drive conflicts, and generally speaking some kind of random element to bounce creativity off of, maybe a bit more depending on the author's feelings and what he's aiming at. So Universalis is 136 Pages 5.5" x 8.5", Capes is pretty small as well; about 160 pages, digest sized. In both cases, a good chunk of the pagecount are play examples and strategy discussion; for Capes, another good chunk is templates for quickly creating characters. Also in both cases, generating new material would only entail writing down descriptions/descriptors; nothing mechanical changes about the game.
The thing is...from a sales/expansion point of view...those games are done, one-offs. I suppose you could maybe sell additional "click-and-lock" templates for Capes in other genres, but at best your talking a 20-30 page pdf/genre. Can a Narrative base generate splat material? Maybe. Fiasco seems to have a zillion playsets or so, but most of them are free, and they only consist of a few pages. Apocalypse World and Dungeon World? Hard to say. There seems a squishy limit to how many classes fit well, and generating fronts is easy. Spells, maybe?
That doesn't mean that you can't have Narrative elements or support in a larger game. FATE is, perhaps, the most famous example now with Dresden Files, Legends of Anglerre, etc. demonstrating the ability for that system to support supplement generation. However, the underlying system is a vague, sloppy, Simulationist system. Depending on the aspects chosen, FATE doesn't have to be very Narrativist at all. I feel similarly about Burning Wheel, although I have less experience with it and am relying on online discussions that BW can be played very Sim and even Gamist (!

So, you're a publisher. You want to publish. You need to generate content for your game...which means proliferating rules. (Thus splat material outselling adventures/world material.) So, when you invent your game, you make sure to invent a game that makes proliferating rules easy....it will have fiddly bits!...and many types of fiddly bits!
Narrativism, IMO, makes fiddly bits difficult. The fiddly bits get too much like scripting, and Narration often approaches events and situations that are too open-ended and hard to write for. To illustrate this to yourself: try to make up an AEDU-like power structure for argument/social interaction rather than combat. Tough, isn't it? Worse, the results are unsatisfying or flat out weird. Notice how 4e flees the fiddly bits when you get into this territory, relegating itself to some comparatively vague skill checks in a skill challenge.* Yes, I know that "Narrativism doesn't have to be rules light.." is the mantra, but...
I no longer think this is choice on the designer's part. I'm looking at the "proof-of-concept" games out there, and I've never heard a whisper of one that handles things in a fundamentally Narrativist fashion, and yet has tons of fiddly bits. Plenty of FATEs, and BWs, which have a Narrativist bent or section tacked onto some other "big" frame, but no version of "social combat" that anywhere near approaches the level of finesse or detail that we're used to seeing for physical combat. If you know of a counter-example, I'd love to hear it.
So, you're left with Gamism or Simulationism (or nonsense, I suppose). Either one can generate or tolerate gobs of fiddly bits. Gamism can be dirt simple, but if you design the substrate well enough, you can leave room for plenty of fiddly-bit function. That's why I think the historical tendency is for Sim. It practically demands rules proliferation. Gamism requires some prep work to create a foundation that does. So, while Sim drives rules proliferation on its own, the fact the rules-proliferation is driven externally, can drive Gamism. At the level of the Table, Rules-proliferation means more ways to look for exploitations/combos to bring about the "win" or score "cool points", which is a gamist urge.
Example: Magic, the Gathering. Totally Gamist structure. Cards are rules, need to sell cards->rules/card proliferation.
Example 2: Power creep in 2e and 3e. Totally a Gamist function, driven and supported by the need for splat supplement sales. (less prominent in 3e than in 2e.)
While 4e supporters look at the explicit math in 4e as a balance-driven thing, I also see it as a defense mechanism against power creep. Having it there prevented them from "accidentally" releasing a later defender that was strictly better than the Fighter. Which is certainly a temptation when you're trying to sell books. In part, this is what made 4e so brilliant, it used a lot of gamist trappings, but actively and openly resisted gamism-creep. Unfortunately, it also managed to be a big turn-off for a lot of people.
Anyway....I guess that's it. I hope that makes some sense to someone other than me.
TL/DR:
Narrativism doesn't support fiddly bits.
Publishers need fiddly bits to support splat.
No 'N' means 'S', 'G', or nonsense.
*A weird version of 4e: Create "Melee", "Missile", and (perhaps several) "Magic" skills. Forget AEDU powers, other than maybe the flavor text. Combat could then be resolved as a skill challenge(s) all in TotM.