As someone who came into the industry in college, the problem with SO was simply that it was too hard to ask a question. They were up your ass about minutia that really didn't matter. Good riddance and can't wait to visit the site and see an EOL static page.

One of the more annoying things about SO was they'd pretty frequently misclassify new questions.

Sometimes a new question was in fact a duplicate and should be closed as such. But in the quest to close duplicates I pretty frequently had to argue with the reviewer that "No, this isn't a duplicate just because these two questions related to the same library".

SO practically rewarded this sort of over-policing which I think is a big part of why everyone stopped using it.

And people stopping using it meant that when a question did actually make it through the gauntlet, it was likely to go unanswered because everyone who knew anything had left the platform.