As a new Reddit user, I really enjoyed your insights on the advantages of having a username on these sites. I think I experience a similar phenomenon on Tumblr. While I tend to stay relatively true to myself on my own profile (I used to have a profile picture in order for strangers to identify me), I know many other users who use Tumblr to curate a particular interest of theirs. There are entire profiles dedicated to shows and celebrities, and I imagine having that pseudonym allows the consumer to focus on the content as well as the owner to develop a space to express him/herself without possible backlash from his/her community outside the Internet.