Perfect objectivity might be impossible, but that's no reason to abandon the goal entirely. Close is usually good enough. Not actively diving into the deep end of narrative causality is the absolute minimum I expect from any game, if it is to be salvageable.
Maybe I'm wrong, I have no way to verify my hunch, but I think you're overselling it. As we've amply demonstrated games fundamentally work for gamist reasons. I'm not really even sure what 'narrative causality' would be or how you would 'avoid' it. Why is there a dungeon? Because its fun for the PCs to go in and loot it! That's pretty gamist to me, and it seems to exist only so that there can be some sort of narrative. The dungeon is the antagonist. I get that you can all pretend that there's some other reason 'evil wizards did it.' Its still there so the PCs have a place to adventure. Dragons exist to be slain, etc.
Beyond that, IMHO you're just taking the idea that only your brand of process-sim can give you the type of game you're talking about. Its not like in my games the IN-GAME answer to why there's an encounter going on is "just because it would be boring otherwise" that's not it at all. The players are going around making decisions about what to do, the DM (me) is presenting conflicts and adjudicating them. Those conflicts arise fundamentally because the characters have unmet needs, even if its just a need for entertainment or gold. While I might throw something at the party if they just go camp out in the woods for days on end, they're basically the driving force. Even if its like my war campaign where the action came to them they were still deciding where to be and what to do. Nothing is illogical, plot has to hang together and make sense after all.
I'd also just like to point out that the same 'anthropic principle' that you invoke for 'why are the characters present in this time and place' works for me too! The characters are at the point in time and space where the fulcrum of destiny lies, they will have to confront hard choices and terrible enemies, or else they will fail and go down to the land of the dead unremembered. All the unimportant boring people that might exist? We don't make up legends about them!
Game mechanics can help here. Instead of providing tool to promote and direct the drama, rules can be made to mitigate sources of bias. Random tables are an example of a tool to improve objectivity.
Meh, I think random tables can be OK, but there's no real difference between a random table and a list you just follow from 1 to 10. I long ago realized that was true for 'random encounters', there's no reason at all not to just make up the next 10 'random' encounters that will happen and put them in a list and cross each one off when you get to it. There's no reason not to just put them on the map too! Sure, maybe they're 'wandering' monsters that aren't 'in-lair', but I don't need a table for all this. There's no drama in random die rolls, and if I'm making up the random encounter table anyway, then what's the difference, I've already dictated what is going to likely show up.
Beyond that I don't see tables as more than idea generators. DMs rarely just use what is on them without any filtering anyway. If you're really stuck then I guess rolling a random something is OK, but I don't get stuck like that, there's always something happening. The world isn't just reactive, its ongoing and its aimed squarely at trying to stop the PCs from getting what they want because again that anthropic principle you talked about, which I just call protagonism.
Truthfully though, if I want to just wander in random generator land why not play a computer game? That's how I feel about it. In our 5e game my character has great ambitions. He's 4th level, but by gosh he's going to build himself a kingdom! Everything that stands in the way is his antagonist. He's got so much stuff he needs to do he'll be at it for 15 levels, which is of course exactly how I hope it goes. I have no doubt, and every expectation that the DM will throw neighboring kingdoms, greedy interlopers, foul monsters, and bands of bandits, and stuff I can't even think of, in my way. I'd be very disappointed if it wasn't that way. I don't want to roll dice and just succeed because hey the random dice said it was easy, I want to earn it.