In other words - as I've said previously many times - Sim is a fake cover for 'GM says' where they appeal to their own authority. It's just the GM trying to hide their authorship of the fiction behind 'this is what would happen' while leaving the 'because that's what I arbitrarily decided' unstated.
I am responsible for making up the details of the village of Kensla a medieval village in my Scourge of the Demon Wolf. Or the Woodford Abbey in Deceits of the Russet Lord. So that part is arbitrary.
But I based everything on how medieval villages worked and how interpersonal relationships between humans work. A player who has never experienced my campaigns played my rules, or read the adventure can use their knowledge of both to get further ahead in the adventure than they otherwise would.
Coupled with how my rules work, I am not in the business of making arbitrary decisions in my rulings. I make consistent rulings. Also I will
This is the essence of what good simulationism means. Because things work in the campaign as they do in life, players can use their knowledge to make meaningful accurate choices at the expected odds (when the outcome is uncertain).
This also allows you to playtest. By gauging the reaction of the players to the rules, characters, and situations that suppose to be simulate some aspect of life.
Finally, you don't need to account for everything to the nth level of detail to make simulationism work. In my experience, there is a sweet place between details and playability that is more than good enough.
I made this work this way dozens of time using GURPS, and OD&D and system whose complexity sit in between the two. Under the worst conditions, strangers showing up at my convention games who don't know me, the setting I use, or how I run campaigns.
Last fall at Shire Con 2022, I had two players show up who didn't know my rules but liked to play Harnmaster, and other medieval RPGs. With their help, the party was able to resolve the adventure in record time mostly through roleplaying.
Some images from that game.
We can talk theory and design philosophies all we want but at the end of the day what matters is what happens at the table and what happens at the end.