A lot of folks are not responding my argument, so I must not be explaining it well. Maybe I should enlist ChatGPT.
Will ChatGPT write the next Great American Novel on its own? No, not as it currently exists. Could it be enlisted to write the next Great American Novel? Quite possibly.
Here's an analogy: most people would agree that Andy Warhol is a highly important artist of the 20th century, despite the fact that much of what came out of Andy Warhol's Factory and was attributed to him was physically done by other artists working under his direction (many other visual artists have worked similarly, from Michelangelo to Banksy). Similarly, we consider Martin Scorsese a great film direction, despite the fact that most of the production of any of "his" films was done by someone else. That is because we recognize the creative vision guiding the process, and we see the other contributions as secondary.
Similarly, ChatGPT gives every human being a personal assistant that is a highly competent and incredibly fast writer. Stable Diffusion and similar technologies are giving us highly competent artists. We still have to provide the imagination and guidance. But how much more can we create, on our own, using these technologies?
Let's go back to the original question. Imagine that I want to create a detailed setting for my campaign, based around, I dunno, penguins. I'm a good writer, and I am capable, but do I really want to invest the time producing a 200 page guide to Pengunia? Maybe, but probably not. But a lot of that writing would effectively be drudge work. With ChatGPT, I am suddenly Martin Scorsese. I can get it produce a ton of iterations on different ideas. I can throw in my own writing whenever I want. I can tweak and massage and experiment. Artistically, I can let ideas build up far faster than I could writing on my own. And I can probably write a pretty cool guide, original to the world and specifically tailored to MY needs, in a fraction of the time.
That's what this offers: incredible creative freedom. Will other things be lost? Yes! Maybe ideas I would have had through writing it the old way will never happen. But that is what happens with every new technology. That does not make ChatGPT good or bad. It is a powerful new tool.