We know Firaxis implemented 1upt to get rid of Stacks of Doom but many civ players feel that solution was too radical. Why did Firaxis not consider a simpler solution: simply have a hard cap on the number of units in a single tile, for example 15? This solution would still allow stacks thus avoiding all the issues with 1upt while keeping the stacks small enough to avoid them becoming "stacks of doom". The cap could easily represent the ability of your empire to manage an army of a certain size. In fact, you could have techs, social policies, city buildings, Wonders that would modify this cap. For example a wonder could give +2 units per tile allowing your empire to have a larger stack.