Are there any circumstances under which you would deface someone's Wikipedia page?

Esperanza Spalding won the Grammy Award for Best New Artist last night and a bunch of reprobates, presumably Justin Bieber fans, went and defaced her Wikipedia page. That’s one way to express your displeasure.

Why do people choose to do it this way? Why do people vandalize other items? What would it take for you to resort to vandalism, virtual or real, to get back at someone?