Modern big-budget games incresingly don't use behavior trees and state machines for their AI anymore. This approach has been superseded by technologies like GOAP [1] or HTN [2]. These are computationally very expensive, especially in the constrained computation budget of a real-time game.

While it's true that game AI is often held back by game design decisions, it's not true that technology isn't holding us back in this area as well.

[1] https://www.youtube.com/watch?v=gm7K68663rA (GDC Talk: Goal-Oriented Action Planning: Ten Years of AI Programming)

[2] https://en.wikipedia.org/wiki/Hierarchical_task_network