If you think civ4 combat was just build a single doom stack and throw it at the enemy doom stack you weren't playing civ4 right. Civ4 combat was, when done correctly, all about terrain and mobility, while 1upt turns it from "where is the most effective spot to put my army and where can I hide my cavalry and reinforcements" to "how do I get this archer to this tile without opening a hole in my lines trying to free it up."
Terrain mattered a shitload, due to multiple factors: defense, visibility, and mobility. The 1upt games have some of this still, but it's completely ruined by the fact that even a small army requires so much space that the strategy aspects become irrelevant in the face of the traffic jam. Shit goes somewhere because it fits there.
Don't get me wrong, I've played a lot of civ5. But the combat is incredibly poor in it and reducing civ4 to "muh doomstacks" as a counter argument is horseshit.