I'd argue that the or at least one major reason for the downfall of Stackoverflow (and not just a catalyst) has been a surge of Indian IT people triggering an avalanche of extremely low quality questions and answers. I've been a big fan of SO since about 2010. Not just didn't mind the harsh moderation but actually attribute to it learning how to properly ask a question. But at some point round about 2019/2020 it stopped being fun due to it going from knowledge base to garbage dump.