Let's start with the joke that came out of last Thursday's game session: If you put a 1st-level wizard in a box with a cat, you will not know if the wizard is alive or dead until you open the box and observe. Unless the wizard's only spell was
detect secret doors or something, in which case he's definitely dead. That's the concept of Schrödinger's Wizard. (If you didn't play D&D back in the olden days, suffice to say that a housecat was, according to published mechanics, the rough equal of a beginning-level wizard character, if not outright superior.)
Okay, now let's move on to
this thing here. The short version is that the author is pointing out a rather serious shift in RPG design, that he describes as "numerocentric" and "protagonocentric." This is actually kind of a serious version of Schrödinger's Wizard. I'm not really convinced about his use of terms, but the concept is fairly clear. Where I would change the wording is as follows:
Some RPGs use mechanics to model a reality independent of any observation, and some RPGs use mechanics to model the interface that takes place at the moment of observation.
To go into more detail, many games (including most that I've worked on) generally treat mechanics as a sort of objective truth. If your character has a Strength stat of X, then he can lift Y many pounds (or kilograms, for you weirdos and your kilodecidecacenti systems). Once a mechanic is established as "true," that's a consistent feature of the world. This consistency is the draw of the system for the players who value such. Of course, since most of these numbers are established as judgment calls and you need some abstraction to make a game playable at all, such games do run into trouble when something fails to simulate the intended effect despite working totally in keeping with the rules. A lot of exceptions are key to making games like this work, because reality itself is frequently inconsistent in weird ways. You also have to accept some level of abstraction — witness any system that utilizes hit points.
Now, the other way of approaching things — one that, interestingly enough, the industry leader shifted over to with D&D 4e — is that mechanics represent a specific time period of interaction. They aren't reality, they're the interface. In a way, they are the "observation" phase: the moment that mechanics become relevant is the moment that all these abstract possibilities represented in the game crystallize down into one specific result.
I should note that the observation analogy is a good one, I think, but it's probably more accurate to say that this is the moment of
adjudication. Mechanics arrive only to provide a ruling: their rulings are not constants in the world because mechanical adjudication is not perpetual. A rule is a tool to interface with a fictional world, not a physical law of that world.
Most NPCs in a system like this don't have stat blocks until they're necessary. A blacksmith does not have "hit points" until someone takes a swing at him because hit points are a mechanic particular to the moment of resolving that swing. The rest of the time, the prevailing "truth" of the universe is that it behaves in a way according to the GM and the players' expectations. No mechanics are needed to explain the blacksmith's phobia of crows or his tendency to rub his belly when he smells a particularly large profit involved. There is a moment of adjudication, basically, as the GM chooses the "correct" response that showcases these personality traits, and this is true of all RPGs: but overall, this approach of mechanics-as-adjudication rather than mechanics-as-consistent-feature moves almost
everything into a similar headspace as personality traits. In a way, it represents how we often create fiction in other media as well: you don't simulate everything in a protagonist's life, you use the medium to depict specific points of interface. Even unscripted fiction like improv theater (or RPGs) uses a mechanic as adjudication: you apply a mechanic like "Clive Anderson reads you a scene from a hat" to select a moment to crystallize.
Full disclosure: I love the mechanics-as-interface approach to gaming. Love it. It suits my running style, and I like that the consistency is up to the group to maintain rather than a ruleset. But I do understand how many other people prefer the first style. And the two styles are so different that they're prone to trigger really strong reactions from their partisans. Someone who's used to the consistency of mechanics that represent universal truths may feel as though he or she is standing on shifting sand in a game where the mechanics say "that's not important" and fade away like
kuroko the moment nobody's looking directly at them. At the same time, someone who likes the idea of mechanics staying the hell out of the way may become frustrated in a game where they're ever-present and given precedence.
It's not just a style issue, I think: it's a
trust issue. That's why people get kind of crazy about it. Going all Schrödinger's on a system can be perceived as a lack of trust in rulebooks and in people who like rulebooks. Preferring mechanics as universal constants can be perceived as a lack of trust in one's fellow gamers. This is not a small thing, I should note: the roleplaying hobby is freakin' rife with trust issues. You could even claim the early days trained people to have trust issues, with a high-lethality game where you had to think like the DM in order to bypass the traps was the main way people played — even before you add in the crap GMs who doled out save-or-die (sometimes without the save) at their whim, often just as part of a power trip.
Varying tastes in style are inevitable, of course. And I think it's a good thing that the hobby supports two styles of play. I find it unfortunate that they're so at odds, though. Anything that adds to the fractiousness of this hobby is sad to see.
Though even that may be somewhat hypocritical of me to say. I love my rules-as-interface style of play. I would be happy to work on more objective-mechanic style of games in future, but when it comes time to run? Give me the wizard stuffed in a box with a cat. That's my thing.