Assignments are usually just a proxy for the skill which we're actually trying to teach or evaluate. The fact that a course assignment can be done by using a chatbot does not mean that the skill which that course is teaching can be done by using that chatbot.

If a coach assigns someone to repeatedly lift heavy weights in order to become stronger, lifting them with a forklift doesn't achieve the goal, because in real life that strength is intended for situations where you won't use a forklift. The same goes for exercising various "mental muscles".