AnonymousIdentity and PseudonymousIdentity? elide common identity cues, such as race, gender, and ethnicity. Many critical theorists, particularly during the 70s and 80s, had great hope the Internet would serve to finally give everyone an equal footing in society's discourse since the common prejudicial lens and filters would be absent or disabled. To a very strong degree, this hope created a myth that informed the software environment that made it happen to some extent. A lot of the reinforcing rhetoric surrounding AnonymousIdentity has to do with the absense of stereotyping.
But the reality is not so ideal. Prejudice may be a visual mode, but culture is a cognitive one. Absent visual cues to forcibly differentiate people, people still weren't free to express themselves as they would on the proverbial street. Rather, netizens quickly normalize to some common style of discourse that is indistinguishable from others in order to fit in. Given the predominantly white American male presence on the Internet, this means that ethnic voices are replaced by an UnbearableWhitenessOfBeing.
See CyberTypes, OnlineStigma, SocialNormalization.