TwoSix
Everyone's literal second-favorite poster
I would generally say the system "feeding into the fiction" doesn't make for a sim element. The system trying to capture and model a pre-existing fiction is much more of a sim process.The class system can fit into a sim agenda, particularly if the classes have enough options available to represent many different ways to accomplish one's goals. In my view, class features feed into the fiction all or nearly all the time, and if they don't a little adjustment can make that happen.
One of my favorite things in the world is watching stories critically with an eye towards translating the narrative, setting and character into game terms. I can look at a character kicking butt with a variety of weapons and a distinct, training-based style and say to myself, "that's a fighter". I can see a character casting a spell and speculate how magic works in that setting. Heck, I can see a character getting hit by a monster and thrown across the room and try to figure out the combat system. More importantly I want to do those things.
IMO, all of that is sim.
WFRP's career system, to me, is much more of a sim element than D&D's class system.