The precipitous decline was already happening long before LLM's dealt the final blow.
> Avoid asking questions that are subjective, argumentative, or require extended discussion. This is not a discussion board, this is a place for questions that can be answered!
https://stackoverflow.blog/2010/01/04/stack-overflow-where-w...
> Certainly on Stack Overflow and Stack Exchange we are very much pro-moderation -- and more so with every passing year.
https://stackoverflow.blog/2012/01/31/the-trouble-with-popul...
> Stack Overflow – like most online communities I’ve studied – naturally trends toward increased strictness over time. It’s primarily a defense mechanism, an immune system of the sort a child develops after first entering school or daycare and being exposed to the wide, wide world of everyday sneezes and coughs with the occasional meningitis outbreak. It isn’t always a pleasant process, but it is, unfortunately, a necessary one if you want to survive. > All the content on the site must exist to serve the mission of learning over entertainment – even if that means making difficult calls about removing some questions and answers that fail to meet those goals, plus or minus 10 percent.
All of this meant the learning-curve on how to participate was high, and this spurred gate-keeping and over-zealous moderation. High-quality but out-of-date information was preferred over lower-quality but more recent updates. When combined with the rapid shifts brought on with mobile development and web frameworks, the answers could easily get out-of-date months after being answered.
I remember a time when StackOverflow dominated every search query. Now we're seeing searches take you to a dedicated forum/discussion board, which feels more appropriate for the current state of the industry.