There's so much unnecessary confusion about persons. In school they make you think that they're just writing styles, but they never teach you what the second person is. They never tell you that it's the pronouns themselves that matter and not who the author is addressing.
Oh, and that article was a little bit off in one regard: they say that some languages have more than three persons, but then they link to a page about Ojibwe, which apparently has just three persons. It simply has an inclusive and an exclusive we, which are still both first-person pronouns.