You're assuming that openAI isn't just gonna add the new questions to the training data.
This is the same thing as synthetic training data.
It doesn't matter if models are trained on the output of the generated data or not. If the model ends up being able to solve newly generated variations, you'd have to admit that it understands the underlying problems.
It's good in automation, not understanding.
I see this more akin to a human faking their way through a conversation.
That works in English class. Try it in a math class and you'll get a much lower grade than ChatGPT will.