To me that's the biggest problem with 1UPT: When the Civ team decided to do 1UPT they didn't think past "this will be a great game experience" to realize that it will require the game to have two different levels of AI. Prior civ games basically needed a strategic-level AI: Build cities, build armies, start steamrolling. Starting in Civ5, the AI had to be capable of winning a Civ-style 4x game AND a Panzer General style tactical game _at the same time_ which is clearly was not able to do. Civ6 is a little better at it but (hello mister no air forces) it's still not 100%.
When you make the game more complex and fun for the player, you have to remember that the AI is almost certainly not going to be able to keep up with what a player can, so you can either super-cheat or you can spend a pile of time making the AI really smart. The problem with a really smart AI? A really smart AI will *always* play to win, never make mistakes, always know how to min-max the game, and will utterly crush newer players, so now you have to reverse buff newer players...
...which leads to the players screaming that the AI is too "gamey" and doesn't "act like they should" when they try to win the game. It's a cycle of complaints that is circular.
When you make the game more complex and fun for the player, you have to remember that the AI is almost certainly not going to be able to keep up with what a player can, so you can either super-cheat or you can spend a pile of time making the AI really smart. The problem with a really smart AI? A really smart AI will *always* play to win, never make mistakes, always know how to min-max the game, and will utterly crush newer players, so now you have to reverse buff newer players...
...which leads to the players screaming that the AI is too "gamey" and doesn't "act like they should" when they try to win the game. It's a cycle of complaints that is circular.