Let me go a little deep in support of this question.
Firstly, Stack Exchange willwould be useless if ChatGPT was allowed network-wide. Remember that SE is a network of communities such that each person seeks to learn more from each other, not just the questioner. Even answerers get to learn by getting improvements from other users. This would be useless if AI could automatically answer all questions, with little error, and ChatGPT has seemed to acheiveachieve this goal.
I hear you saying "But we've got Google!". Well, for starters, most of my programming answers were basically searches into Google, but they mostly redirected to Stack Overflow and related webpages.
Secondly, AI is still not yet perfect. So although the range of error is small, now again here we're talking about lots of answers. That means, small translates to a (somewhat) big amount.
Thirdly, most of the issues concerning SO about AI pretty much applies to the entire network.
That's all I've got to say.