This is often used by inexperienced users to justify non-canon things being canon. As said before, having the same history as the show doesn't mean it's canon, every comic, game, etc. has the same history and expands over plotpoints and stuff, with specific references to eps and all too, it doesn't matter, KND: Kids Next Door, Billy & Mandy, Samurai Jack, FOP and a long etc., what better thing to fill space in magazines than comics like this, if they didn't get their actual comics. For example
here are the Untold Tales From the Big Superhero Wish!, a comic that goes over what happens after the ep
The Big Superhero Wish!, as a direct continuation of that story, same with some comics from Pixar movies that go over what happened after them, or the
Nightmare Before Christmas and
Toy Story Wii videogames again re-taking their stories by their end, it doesn't mean anything. They're following those stories under their own continuities, I am stating the obvious here.