It is simply a cat-and-mouse game: if the most primitive usage of AI will be blocked, then we will have more advanced cases, where to tell a difference, you will have to do something more, than just passing the content through some detectors: you would need to find patterns, which are human-specific, and can be seen, if you technically know, which answer is correct, and which is just a hallucination. And that kind of things are beyond what automated tools can "understand".
The idea is (at least for me) to make AI spammers do more work than which will be required for a good post on your own. If anyone is scraping the whole thread and making good efforts to go through improvising the prompts to write something helpful and then going through the efforts of humanizing it, IMO, he will not be able to sustain it for long. It is just simply not economical, and if he is able to do all that, I think he is genuinely being helpful.
BTW, you don't remove the fence around your field thinking that few clever animals will bypass that, fence serves a purpose for majority of animals.