However, the closest one can come to crispiness here is to take all games to be simulations
You are confusing RPGs with simulations.
There's already a genre for simulations: It is called "simulation". Of which RPGs are not a subset.
Games can be both, though, I'd say they are one of the few genres that don't have to reduce each other's share like e.g. Action and RPG do.
The essential RPG identifier always was and will be: Outcomes of actions are determined not by physical player skills, but by the underlying mechanics, which are influenced by the player's choices. In other words, it's the character(s) that does actions, not the player.
However, these abstractions are not technical limitations or flaws, but willful choices of game design. They are the entire point of the genre: To allow meaningful player choices/agenda through an abstracted system (usually character & combat system).
In a simulation, you could very much have the player determine all the actions through physical skill.
Imagine, e.g. a racing sim via steering wheel setup. It would clearly be a simulation, but could never be considered an RPG.
If, however, you didn't directly control the character's actions but only issued indirect commands and an underlying system determined the outcome (say, a racing driver character system), you could have a probably very unfun racing RPG on your hands. Which would now be both a simulation and an RPG.
If you now took all the simulation aspects away (simulated movement of cars, physics, etc.) but kept the indirect command issuing & character system - it would no longer be a simulation, but still an RPG. And a probably terrible game, but that's besides the point.