Just to put that into perspective again: DOTA, Starcraft, Chess, Go or whatever are by far more trivial that HoI4 in regards to AI.
Fit example, in DOTA or SC the AI know the exact number of Hitpoints any unit has with the exact number of damage it does and the exact timing it has with attacks. With this ruleset, it is absolutely trivial to calculate a path through a tree of possible decisions for the optimal outcome resulting in perfect last-hitting or "microing" the optimum number of units to oneshot another.
These rulesets do not exist in HoI4 because Dijkstra/Prim kind of solution (take the optimal next step every time to reach optimal outcome) won't really work in a deterministic way of thinking.
In a sidenote, the GO algorithms got so good because they played thousands of games against themselfes. If you'd remove a Column from the Board, the "AI" would need to learn all over again. Everything. Because the ruleset changed.
Current AI is just a glorified decision-tree with statistics mixed in based on huge amount of data.
In the end, it still comes down to things like "If lastsuccess > 0.5 then try again and modify succesrate when finished".
TL;DR: It's about complexity of rulesets und available data including processingpower of said data. Mark my words: Cars will drive themselfes better than humans way before you get a competitive, non-cheating AI in games like HoI4. That's because the ruleset and availability/mass of data is trivial in comparison.
Fit example, in DOTA or SC the AI know the exact number of Hitpoints any unit has with the exact number of damage it does and the exact timing it has with attacks. With this ruleset, it is absolutely trivial to calculate a path through a tree of possible decisions for the optimal outcome resulting in perfect last-hitting or "microing" the optimum number of units to oneshot another.
These rulesets do not exist in HoI4 because Dijkstra/Prim kind of solution (take the optimal next step every time to reach optimal outcome) won't really work in a deterministic way of thinking.
In a sidenote, the GO algorithms got so good because they played thousands of games against themselfes. If you'd remove a Column from the Board, the "AI" would need to learn all over again. Everything. Because the ruleset changed.
Current AI is just a glorified decision-tree with statistics mixed in based on huge amount of data.
In the end, it still comes down to things like "If lastsuccess > 0.5 then try again and modify succesrate when finished".
TL;DR: It's about complexity of rulesets und available data including processingpower of said data. Mark my words: Cars will drive themselfes better than humans way before you get a competitive, non-cheating AI in games like HoI4. That's because the ruleset and availability/mass of data is trivial in comparison.