It's coming at the problem from different directions. The documentation gives you the general bottom up approach, but lacks details and examples. SO shows what

It's coming at the problem from different directions. The documentation gives you the general bottom up approach, but lacks details and examples. SO shows what it should look like at the end, and adds details on edge cases that the documentation just glosses over. But you can never find exactly what you want, so you combine those two, a working end result, then modified using the documentation, to get what you want in the end. If you already have a working pattern that you're just modifying, you might get away with just looking up documentation. If you already have a strong foundation and know exactly what you want to do, then you're just looking up the syntax. Maybe another analogy might be, learning vocab to better express your thoughts, vs looking up the exact spelling of a word you already know.