The people who most heavily rely on pseudonyms in online spaces are those who are most marginalized by systems of power. “Real names” policies aren’t empowering; they’re an authoritarian assertion of power over vulnerable people.
update 14. 6. 2012 – da das Thema nicht unaktueller wird: Geek Feminism Wiki, Who is harmed by a “Real Names” policy?.
This page lists groups of people who are disadvantaged by any policy which bans Pseudonymity and requires so-called “Real names” (more properly, legal names).