I’m an outsider, that is, I don’t belong to any of the big social networks; Facebook, Twitter, Instagram, Tumblr (soon to be buried by Instagram), so my perspective may not matter much in the over-all scheme of social networks, but, I think you nailed the crux of the matter in your sentence in the sixth paragraph; “After all people don’t go to social networking sites with the best features — they go to the ones that all their friends are on”. My brother tried to petiton me to join Facebook to almost a feverish fanaticism as if he were an evangical representative of Facebook trying to convert me to the almighty Facebook religion. I didn’t move in the same circle of his friends, though, and now he is gone, so there is no point in it, if ever there was one. I belonged to LinkedIn once, but, the shoe didn’t fit. In my opinion, Google Plus was always destined to meet the same fate as its predecessor, Google Buzz. Even Facebook is on the life support system of Instagram.