Hrm. My opinion is that complete accuracy isn't all that fun. Folks have used tax records to do analysis of, say, how many farmers it takes in a village for a blacksmith to be present, and so on and so forth. It was a lot more than you might imagine.
On the other hand, looking at the D&D 3.5 Dungeon Masters Guide 2, they have finally fleshed out Saltmarsh. Bizarrely, a town of less than four thousand people actually has an assassins' guild, with roughly ten members. Do they take turns, each assassinating one person a year? Because that's roughly how infrequently it would have to occur for their little club to escape notice. Hardly worth paying dues for, sitting around, discussing that murder you managed five years ago and how you look forward to one in another five.
Take a look at city-building ... in most games you rarely see the hub-and-spoke develop around a port city, despite that being a prevalent pattern, or the unique feel of isoheight versus steep streets in a hilly region (the San Francisco pattern). If you watch city maps over hundreds of years, many forces are at work, and I think they might be simulable but I don't know if the end result would be enjoyable enjoy to warrant it.
If you look at our actual cave ecosystems, troglobionts, which are adapted for living strictly in caves, are typically quite tiny. There's simply no food down there! Resources are scarce. Hence you would get no gelatinous cubes or hook horrors or carrion crawlers stumbling around the caves, lurking about, waiting for adventurers or the average bear. Instead you get some very small, pale shrimp. This is not exciting for the adventurer. Some handwaving of a source of energy called "Faerzress" eventually takes place and is only vaguely acceptable if one does not look hard, serving as kind of a bottom trophic level for the game.
The balance between actual plausibilty and what one might call "fantastical satiation" is quite difficult. Your large-sized dragon, perhaps your standard-issue Vermithrax Pejorative, would need something like a log flume ride of virgins delivered straight to its gullet to sustain its bulk, not to mention the caloric expenditure. Clearly, this isn't very satisfying for your story-telling, either.
The balance is rough and I suspect that nitpicking in the name of accuracy can undermine most of what is constructed.