Except with stack overflow you can use your experience and pick the best code and onboard the comments discussing various aspects of the different answers. The LLMs don't do that.
They can just spit out whatever the fuck they want and there's no guidance or votes or comments. Just an averaging of everything.
And here I've tried generative LLMs about once a year and every time I go "what the fuck are people smoking to think this is good".
I think everyone insisting all this stuff is providing value are legitimately idiots who haven't spent even a half second thinking for themselves or about the future or the quality of their work.
I wish I was more dumb and saw these products working like you insist and didn't have to spend half my time rejecting AI slop PRs that genuinely don't address anything.