Mathalamus
Emperor of Mathalia
So you move your doomstacks unit by unit? We're talking about same level of automated movement. There's no inherent reason why you couldn't group multiple units and send them with one click to location several turns away while maintaining formation or reshuffling into it upon arrival. It would just need a bit of work with pathfinding AI, which is where 5 failed.
Also, the carpets of doom are inefficient solution stemming from bad AI and players stuck in the old mindset. I found that small, properly commanded groups (about 9-12 units+GG) are more cost-effective. Of course you might need a trail of reinforcements for meatshield troops, but that's not different from Civ4. And there's no reason why the game couldn't be balanced around smaller army sizes.
And frankly, I do not feel that it diminishes other aspects. There are 4X games with more complex battle systems that work well, like for example Master of Orion 2.
you move the doomstacks by stacks if all you need to do is move them. itd when you attack that you need to use particular units in said doomstack.
Civilization 5 was balanced around smaller army sizes. unfortunately, it all makes the game glacially slow, to the point where you spend 7 long turns building a warrior. just one warrior. and also, the AI cannot use the 1 unit per tile effectively. or at all.
so, civilization5 nerfed production yeilds, greatly increased production requirements, made a complete mess of combat, only for the AI to be functionally garbage when it comes to actually using it properly. any player with a scratch team of a couple ranged units, one meelee, and one artillery can probably steamroll the entire game with just that.