Comment by phendrenad2

AI didn't kill SO, SO was already declining due to toxic users and lack of organization. The toxic users were dunning-krugerian anal-retentive mini-Napoleons who delighted in locking anything slightly off-topic and merging slightly-related questions, and the lack of organization was a tendency for people to give incorrect answers but still get upvoted (due to Google search surfacing the page in the wrong context).