Stringy, you make excellent points! Also with Facebook growing and including a lot of older and younger people, it is making online interaction seem a lot less weird to those who might not have understood it before. I now play Farmville and chat with with my old Girl Scout leader, co-workers, aunt and cousins, cousins' cousins, old boyfriends, kindergarten classmates, etc -- people whom I have not had face-to-face or any contact with, really, for over 30 years. So for them to understand I might know other people just from meeting them online is not such a leap for them anymore.
Besides, I braved my father bringing up at a family party that he had stumbled across my fashion blog and started teasing me about taking so many pictures of myself. Once you've lived through that moment, telling people about a fashion site where you are NOT the focal point is pretty easy! (That was his point of annoyance, that I wasn't updating my photo blog and was only doing self-portraits instead. LOL!)
Maya, I have a large social circle BECAUSE of my online interactions. All of my local friends, except for Shopping Friend, are people I met online. All of them. And most of my girlfriends are unmarried; I am one of the few with a spouse. Actually, the one really noticeable thing about us is most of us don't have kids! But beyond that, you would not know from looking at us we still often interact more online than we do face-to-face. And no one really cares.
I think it's kind of like when you are wearing a bad outfit that you don't like: it seems like it's the most noticeable thing about you, that everyone can see and is passing judgement on your horrendous taste, but the reality is everyone else is usually so caught up in their own anxieties or dramas they don't notice anyone else's.