>>49190
I think their process is to make a basic mechanic for all in the base game. Which makes the game works, but interesting only enough to make players see potential. Otherwise it's bland, and nonsensical to some nations or cultures, etc.
Then create DLCs to add more flavour gradually. They not just serve as new source of income, but they make the product marketable for the long run, extending the lifecycle and the hype by years.