Whether brains or LLMs, claiming that "in reality all they can do" is X seems dubious, given that a system can have properties that its constituents do not have

Whether brains or LLMs, claiming that "in reality all they can do" is X seems dubious, given that a system can have properties that its constituents do not have on their own. As an explanation of the emerging complexity of what "they can do" it is fundamentally unsatisfying.