Your assertion that cities aren't natural is more of that "noble savage" bullshit.
Every society, everywhere in the world, regardless of local culture, builds one as soon as they have the tech to do so.
Communities =/= cities, hence why I specifically noted nomadic cultures as an example of large communities that don't naturally form cities. Also, your terms aren't anywhere near defined enough for these assertions to make sense. 'As soon as they have the tech to do so' means... what, exactly? As soon as they know how to build houses? What about cultures like the Mongols? They knew how to build houses just fine. They were skilled enough engineers to build fleets of ships and try and invade Japan, but they remained nomadic and mobile long after becoming one of the richest and most powerful empires on earth. What about many of the ancient Arabic and Mesopotamian cultures, who were skilled enough stone workers to carve huge temple complexes that have lasted for thousands of years? Despite all that ability, the overwhelming majority of their populations were transient and didn't congregate in cities until empires like Persia and Rome came along and subjugated them. Even then, many of their descendants remain voluntarily nomadic
to this day. The assertion that cultures just naturally start congregating in cities as soon as they have a nebulous level of technology points (the world is just a very advanced Paradox Grand Strategy title, after all) simply doesn't hold up to any level of historical analysis.
Cities are just what you get when technology removes the natural "cap" of how big a given community can grow before it runs out of food or produces too much waste to handle. Agriculture moved us from teepee to thatch hut, and tractors then moved us to apartment block, it's a natural evolution.
The more you use the word 'natural', the more I think you have no idea how to use it. There was nothing 'natural' about the expansion of cities in either the ancient or modern eras. Rome is a great example. Rome was one of the largest (and filthiest, and most disease-ridden, and most prone to spontaneously burning down) cities of the ancient world, and it grew directly as a result of advances in agriculture. But the driving force behind those advances had
nothing to do with nature. It had to do with greedy Patricians forcibly buying up gigantic tracks of land and turning them into enormous slave-plantations. The disenfranchised poor were then forced to migrate inwards to the cities, where they survived mostly on the grain dole. It was
not their choice to migrate, nor did it improve their lives, nor did it result in a 'more advanced' system. It resulted in several near famines, and the eventual destruction of the Republican government via a populist uprising.
In the modern/industrial revolution era, the pattern remains the same. Cities were important trading and economic hubs, but they were not viable for long-term habitation and internal expansion until the great industrial barons began creating tightly regulated (and
staggeringly unethical) industrial programs that forced the agrarian populace to either convert to the new method or die of starvation. Just like with ancient Rome, these men monopolized the resources necessary for massive economic expansion and gave people no choice but to conform. They bought up agricultural land and constructed whole towns that operated on a tightly planned internal economy that made sure the workers had to do their turn in the mines or factories in order to pay for the food that in previous years they'd have been producing on their own. 'Advancement' of this nature has always been artificial and top-down, it has
never been natural.