A_Carrington
Explorer
The same could be true in simulation of reality, not just a genre simulation.
Here's an example to demonstrate the difference between two ways the word is being used: a the player of a high-level character wins a contested strength check to break free of a flying dragon, and a result falls thousands of feet. He takes the maximum of 20d6 damage, and lives. Which was part of his plan; he knew 20d6 couldn't kill him. The GM frowns, says "that's not realistic" and rules the character dies.
The GM broke the simulation in order to simulate reality.
If the character has more than 120 hit points, then it is realistic.
Realistic doesn't refer to the real world. If our hypothetical GM disagrees, and assuming that realism is always his primary decision making metric, then this situation never would have come up in his game, since there never would have been a dragon. If realistic refers to the real world, then dragons are not realistic.
Either the rules define how the game works, or they do not.