Interesting read! Although I think I'm with Poole on this one; while most people have a simplistic approach with primary identities, it's actually pretty easy to change the "facets" of ones identity, personality, attributes, etc. both online and off. Depending on how people prefer to present themselves, they will assume such identity (I once managed to convince people offline that I was a Prince from Rajhasthan by modifying my speech, attire, thought process and body language, and pulled a successful prank for heck's sake). And depending on the circumstances, they will change their facets. After all, we only know people by how they present themselves, not who they really are, and it's pretty easy to judge them as "simpletons" even if they prefer to use primary identities for the sake of privacy -- but their primary identities are always, constantly refined.
For instance, you probably know me as a youthful clown (or a "gentleman thinker"; depends who you ask), because that's how I like to present myself; but what would you know about my skills, my vivid armory of personalities, my thoughts, my clothes, my preferences, etc.? I can easily be the best dressed Baron one day, and a slum wretch the next.
(Note: The above paragraphs relate to "People are like diamonds" issue; below relates to Social Networking Names.)
However, you're right on one regard that for most people it's simply useless, especially online; then again "names" alone don't establish identity, but helps facilitate it -- people find it convenient to let others know who they are rather than not. Although, unless you live in UK, what if you'd like to "upgrade" your identity by stating a, say, Pen Name? Mark Twain would sigh in disbelief if his account was deleted on Google Plus.
And yet we're stuck with the dilemma of whether people would be true to themselves. Some take facetual (is that a word?) identity to levels they can't handle and stumble, but would almost never hone and re-invent themselves for who they are or what they represent. Facebook and Google Plus help them re-invent themselves. However, as I mentioned before, they also somehow restrict much "empathetic connection" with people compared to how you're used it in real-life. This isn't much of an extension, but more of degeneration. Then again, it's just me -- I abhor mixing social life with consumerism and marketing.
