Can't disappoint Ammokkx by ignoring this one, ei?
So, I'm going to start off with a quip. Numbers don't lie, but interpretations do, unwillingly or not. Why I think the point is utterly missed, I think has been articulated well across the thread so far. This isn't to say there aren't things I acknowledge. In fact, I agree with much of it until it gets into the claims made from the title. I believe there has been a horrible misdiagnosis, even if the factors presented I do think apply to some extent. But they're nothing you don't see across roleplaying in general. "The numbers" based on those factors I find are little different, and if you disagree, it is time to present those numbers so confidently referred to and explain precisely how the factors applied over anything else.
The very premise of this idea is nonsensical and removes the incentive to succeed in lieu of a "functioning narrative." In a narrative based Nation RP--in the equation of deciding battles--you are asking someone to intentionally lose in the interest of story. This forced collectivization can cause resentment or even a tug of war of narrative favoritism in the vein of: "I lost last time, you should lose this time."
This is a serious issue with roleplaying in general, where players in combat situations simply cannot bring themselves to take a hit for the good of story or their own character's development. However, even as this element exists on the guild, there are many others who are advanced to the point of recognizing that this is a primitive way to roleplay, like poorly written self inserts. By thinking this way, you are subverting the very idea of roleplaying, injecting a conventional game into a medium where it simply results in conflict unless that premise was part of the OOC in the first place.
Rest assured, the numbers indicate the amount of stat-based roleplays that kick the bucket is just as bad as narrative-based ones. This is beyond the concept of nations, and the reason goes well beyond what you tried to shoehorn here. It's not that people don't do this, it's the implication that it's unavoidable or standard, and that it supersedes more generic reasons why roleplays tend to fail.
Where you especially lose me is when you insist NRP should be viewed as a game as compared to a story. No. People abandon games as easily and for as fickle reasons as they abandon stories. People can do it both ways and both have their successes and failures. The Guild (and other places I'm sure) tends to err towards the story end, since as already stated, people who want to make a win/lose game out of it can go play Civ and other things. There is absolutely nothing wrong with this.