Facebook was always lame, it was a utilitarian communication tool. It's like calling hammers or wall calendars or trash bags lame.
It's similar to the argument you here when people say "they youth arent into facebook anymore, now they use xxxx." That's nice and all, but as long as they get facebook when they graduate high school or go to college, facebook wins. It doesnt need to be hip and cool if its the network gluing everyone together. Did the white pages or yellow pages need to be cool to be useful?
I was on Facebook back when you had to have a college email to be on it. It was were you could go to find out the name of that cute girl in class. It was also when social media was still a new concept. MySpace was a much bigger deal at the time, but Facebook was the first place where I could meet people my age nearby, organize a party, find out what was happening around campus.
I have not doubt Facebook will continue to win for a long time. But I think kids retreated from social media to avoid their parents. Everything is owned by a handful of companies now, so it doesn't really matter where they go I guess.
Facebook wasnt cool. The people on facebook were cool. I believe facebook took off for two reasons. One is the one you mentioned, that it was exclusive. Two was that it was the anti-livejournal/myspace. No css, no glitter, no strobing, no sound, no hard to read colors, no moving elements around the page. IT standardized where and what functions looked like, and acted more like creation software (photoshop) than the output of the document layout tools. Facebook was utilitarian in that you couldnt customize its look, you couldnt express yourself. It took itself as a white pages, not a portfolio.
One of the best features of that era was the network pages - your college email gave you access to an area solely for your college, where events could be organized, had a posting board, I think its own gallery, etc. When it went public-access this was among the first things to go, replaced with the more generic groups.
