When it comes to the simulation argument there's something fundamental I don't understand. Hit Points, to me, just measure durability. We can split it up however we want but in simple terms it's how long can you survive attempts to kill you. Apologies if this sounds dismissive, that's not my intent. I just really don't understand why HP only affecting whether you're conscious or not makes a difference.
So I was thinking about games that are simulations - specifically cars and racing. There are some race games that don't care about fuel, others that only require that you fill up every so many laps and games that try to be hyper realistic and even calculate in how much gas you have and how much it weighs.
So on one end you have Mario Kart and on the other extreme you have games like Asseto Corsa (AC). I wouldn't consider Mario Cart a realistic simulation (you may not consider it a simulation at all), but AC is so realistic that some real world race car drivers use it for training.
AC goes so far as to not only track how much fuel you use, but what the remaining fuel weighs because it affects the dynamics of the car. But let's say there's another game that does everything AC does (including refueling) but doesn't consider the weight of that fuel. Let's call it NAC (Not Asseto Corsa). Would they still be considered a sim? Because that, to me, is analogous to HP. HP measures durability, it just doesn't measure every aspect of durability that it could much like the sim that doesn't track the weight of the fuel.
But the definition
@Hussar posted was "A system where the system produces information for the user beyond references within the system itself." Which ... doesn't really mean anything for me. In my dualing car sims it's just a matter of accuracy of the sim not whether one is a sim or not. The only information the player has is how much fuel they have in the tank. They know that when they get down close to the E on the gauge that they need to make a pit stop.
The AC simulator has information (weight of the fuel) hidden from the player. NAC does not hide that because the weight of the fuel is static. Yet other games just ignore fuel and factors like tire wear altogether but the cars still drive and function close to world cars. Further down the spectrum you get Mario Kart. At what point on the spectrum from Asseto Corsa to Mario Kart do you go from racing sim to not racing sim?
I see tracking the weight of the fuel or not similar to how your remaining durability (HP in D&D) may affect how likely you are to achieve goals in some games but not in D&D.