Well, those are just examples, and I didn't search when I listed them. I know for a fact that, even after searching, I did have problems with deploying to Google Play.
Whichever way you look at it, a forum is not a very effective form of storing reference information. It does work, but it could be better.
Also, don't underestimate how a cookbook could be "inspiration fuel". I have several apps, and casually browse through the cookbook. Suddenly I see something and think "Hm, I could add that to my app...". Of course, you can do that with a forum as well, but that more or less requires you to be there when the issue is discussed, because you are not likely to search for something you don't know exists.
What I believe, is that, by creating a place in the wiki for such things, people will add content, either original content or content from the forum.
That said, the most important item on the list is context sensitive help. I miss being able to just place the caret on a keyword and hit F1 and get relevant help immediately.