What we miss the the middle ground. And that is open for the taking! (hint)
SO is transient and disposable. It is about the error message of the day and by chance hits the language/pattern of the year. Wikipedia is about stablished knowledge already accepted and published. The open spot in the middle is about accepted techniques for the pattern of the recent years. Those are filled currently by random blogs, posts and news aggregators.
Their community management tools are awful and the philosophy they and the moderators abide to is that questions/answers must be closed as soon as possible.
For example: take one question such as "how to do X in Y". The answer today is "not possible". it is accepted. done. Tomorrow it is "now you use Y.abc" and that old question will never be updated because the person who asked is not interested anymore, or worse, it might even be locked. This is a very common pattern. There's also thousands of the "A: copy and past this, which i do not understand either" which completely kills any knowledgeable discussion.