But after the conquest, it was quite hard for the Ottomans to keep control over Egypt and the Mamluks kept a lot of power, which could be shown as an estate or IG
And all the other conquests where people were just conquered, not "had their ruling class maintain functional control"? You're still, somehow, managing to miss the point. You cannot have infinitely recursive mechanics for every possible scenario. For every example you give, there are a dozen others where something completely different happened. Game mechanics need to work broadly.
The difficulty of administering all that land, rather than conquering it, is the main reason no one ever did a WC.
No, the main reason no one ever did a WC is that they didn't have a near-omniscient overseer with constant insight into things like the mindset of an entire population. Real empires hit roadblocks—there is no magical barrier where they just "can't administer it", there are empires that found ways of administering massive territories that could easily have scaled. They just usually either hit a rival with the same idea or a cascade of errors.
Alexander and the Mongols conquered huge empires in very little time and then they broke up.
I love when people post examples that show they just... clearly don't understand what they are talking about.
Alexander didn't go and just carve an Empire out of nothing—literally all he did was beat the existing dynasty of the Achaemenid Persian Empire and take over. Most of it he didn't even conquer, the local satraps just went "okay, guess we have a new boss now. His empire was just an existing one, plus Greece and a bit of India.
Which kind of undermines your whole thesis that "Empires fall because of administration". The Persians had ruled that Empire for 200 years by that point. It fell apart because the new guy died at 32 without an heir and with several possible successors just strong enough to resist each other. Without that clusterfuck, with one successor, odds are the Empire just keeps working. Because it literally had been for centuries before Alexander was born.
Weird how you try to mention Alexander and the Mongols, but not, say, Caesar and Augustus. Here is a map of what Rome conquered within a single generation and they held those conquests for centuries. Or the Early Islamic conquests, which were also held for centuries after incredibly fast invasions.
It's almost like Empire building is incredibly complicated and the idea that it just "can't administer after a certain point" is naive. Empires stop for complicated reasons—trying to boil them down into something simple enough to be a game mechanic, then declaring "this is always true" shows a genuinely painful determination to ignore history and the hundreds of smaller things that impacted the larger.
