Let’s recap really quickly: wanting to and being able to use your legal name everywhere is associated with privilege. Non-exhaustive list of reasons you might not want to use it on social networks: everyone knows you by a nickname; you want everyone to know you by a nickname; you’re experimenting with changing some aspect of your identity online before you do it elsewhere; online circles are the only place it’s safe to express some aspect of your identity, ever; your legal name marks you as a member of a group disproportionately targeted for harassment; you want to say things or make connections that you don’t want to share with colleagues, family or bosses; you hate your legal name because it is shared with an abusive family member; your legal name doesn’t match your gender identity; you want to participate in a social network as a fictional character; the mere thought of your stalker seeing even your locked down profile makes you sick; you want to create a special-purpose account; you’re an activist wanting to share information but will be in danger if identified; your legal name is imposed by a legal system that doesn’t match your culture… you know, stuff that only affects a really teeny minority numerically, and only a little bit, you know?