Idk anything about any of it. But, what if open AI is "bad" at ward placement because it plays itself so much, it already know exactly where it would be if it were the other team?
The developers talked about the bad warding, and it's a combination of them actually being bad at it, and not knowing how to manage their inventory so they'll just plant wards in order to free up inventory space.
The game vs. Pain clearly demonstrated how humans can use wards to gain an information advantage over the bots that otherwise had a great chance of winning the game.