with respect to the "moderation is the cause" thing... Although I also don't buy moderation as the cause, I wonder if any sort of friction from the "primary source of data" can cause acceleration.
for example, when I'm doing an interenet search for the definition of a word like buggywhip, some search results from the "primary source" show:
> buggy whip, n. meanings, etymology and more | Oxford English Dictionary
> Factsheet What does the noun buggy whip mean? There is one meaning in OED's entry for the noun buggy whip. See 'Meaning & use' for definition, usage, and quotation evidence.
which are non-answer to keep their traffic.
but the AI answer is... the answer.
If SO early on had had some clear AI answer + references, I think that would have kept people on their site.