Well their AI could do MUCH more than it can now, but they nerfed their own AI down to the point it is now. Why?
"While Original Sin's NPCs follow scripts, its sequel's AI constantly makes calculations to determine the best way to murder the player. That also makes it a surprisingly good teacher. "In Original Sin 2, the AI will always know what will happen when it throws a fireball at an oil barrel. What was cool, and we saw it pretty early, was that the AI started teaching players new mechanics. Even if you didn't know anything about the surfaces or how any of this works, you'd see the AI electrifying and freezing water or exploding puddles of oil and poison. You could learn just by watching."
The AI could be too smart, though. "Our combat designers had to remove crowd control from the AI," Vincke explains, "because it focused on one character, made sure to destroy their physical and magical armour, and then would start to control it, then kill it. That wasn't fun because one guy was dealing with everything, but it was a dominant tactic. So we had to nerf it a lot.""
Source:
https://www.pcgamer.com/the-making-of-divinity-original-sin-2/ 
