It doesn't have anything to do with LLMs. It has to do with shifting one's focus from doing good things to making money. Joel did that, and SO failed because of it.

Joel promised the answering community he wouldn't sell SO out from under them, but then he did.

And so the toxicity at the top trickled down into the community.

Those with integrity left the community and only toxic, selfcentered people remained to destroy what was left in effort to salvage what little there was left for themselves.

Mods didn't dupe questions to help the community. They did it to keep their own answers at the top on the rankings.