Mark Zuckerberg says that the philosophy of facebook is that people only have one identity. I think then it's fair to say he couldn't have had JWs leading a double life in mind.
I was careful not to add any JWs to my page, so I thought I should not have any problems. I did however add friends and family, including family members who are former Witnesses and some who are related to current Witnesses. And I added friends who know I no longer believe in the Witnesses.
My sister (who has never been a Witness) wrote something that "tagged" me. It was a set of questions she was answering including something that asked her to write about her brothers, and she mentioned about me being religious and being a JW. It makes me sad and embarrassed because my other friends who know I don't believe in the Witnesses any more may have read it.
What are they going to think that my sister doesn't even know that I don't believe in the Witnesses any more? I feel sorry about that, but I really saw no need to burden my sister about my religious angst. Plus we have relatives in common who are still JWs, and I saw no point in opening up the issue where it might cause problems. I thought she might have taken a hint when I bought her Christmas presents the last couple of years, but apparently not. Apart from the JW stuff, what she wrote about me was pretty sweet, and I don't want to correct her about me not believing in the Witnesses in a "wall" response, first because I don't want to embarrass or upset her and second because my cousins might read it who might tell my aunt... which might get back to the elders or otherwise cause problems.
I don't think it's just JWs leading a double life or sneaky adulterers for whom facebook's "one identity" philosophy may prove incongruous. No one has a single identity. We are all different things in different situations. And aren't there good and valid reasons for emphasizing certain aspects in some contexts and not dwelling on them in other contexts? I think so. This "one identity" philosophy does not really promote honesty, it promotes a fake display of tranparency, when no life can be authentically transparent to all at the same time and in the same way.
I doubt the "one identity" philosophy really was a driving force behind facebook. It sounds more like a post hoc pseudo-philosophical justification for the pre-existing architecture of the site. Despite its current popularity, I think the rigidity of facebook in not being able to reflect the complexity of modern notions of identity is a fatal weakness. Alternatives that more comfortably fit modern identities are bound to arise and displace it.