My thinking is that from a studio's perspective it may be like a proof of concept that AI can get close enough to do what they care about make a passable imitation that gets buts in seats that will generate ad revenue or ticket sales. Fundamentally they aren't really concerned about producing quality material as long as it sells, so if the AI can get them to something kind of good its likely worth their attention. I think that's what writers and actors are concerned about and that is why even an unfunny south park episode is a threat. Fable can say their work is research all day long but their goal can easily change the second a studio shows up with a check in hand.

Also it is not clear here is how much human editing and tweaking was done after the AI was finished with it's part. I suspect people kind of helped the AI get to a final product, but without them disclosing their procedure it's hard to know.