Stack Overflow refuses to provide answers for:

• general questions (when you don’t know where to look for) eg. how do I go about …?
• understanding concepts as different people explain concepts differently eg. what is …?

Specific questions and quick fixes are the faster changing kind of knowledge you can have. And Stack Overflow consistently refuses to update old knowledge.

So, in practice, it's good for:

...

But anyway, some ecosystems documentation are worse, so SO wins.