SE/SO has been on the decline for a long time now. They pivoted to find more ways to monetize the answers and started enshittifying, trying to appeal to business clients and money-people instead of the users and developers who built the knowledgebase. It was good when it felt like a community helping each other, it fell off when it felt like a company milking you to build out their monetized wiki.

At this point, from their perspective, the biggest fuck up was not locking down SE from scrapers and building their own AI. It is in every way the same situation that Reddit is in, just with a more focused and higher quality data set (and fewer, arguably “higher quality,” users).