MySpace is a great example I use frequently. One difference is the explosion in smartphones has made Facebook a real time interaction experience for millions of users. However, the “cool factor” is definitely real and one with many examples of explosive growth and precipitous declines. ICQ, AOL, MySpace, FreeRepbulic (joking) etc.
Yeah, but what kind of interaction? Telling people where you're eating dinner, showing pics of your kids swim meet? No one cares except those close to you, and they can communicate with you in a variety of other ways that are more direct and less intrusive than Facebook. I can see it as a way for family and close friends to stay in touch, but that's not a growth strategy.