Hmm.. Wikipedia says: From 2005 to 2009, Myspace was the largest social networking site in the world.
Then again, Myspace (and most social media) isn't an app for synchronous communication, you logged into it and see who's interacted with your content (or comment). OK then someone invented notifications, and the smartphone (which went from bookish BlackBerry to hip and trendy iPhone in 2007-2008) would bother you.
In the old days of AOL, ICQ or MSN and not always-on-internet, you weren't reachable 24/7. I think one of these didn't even have offline messaging, meaning, if the other user is not online, you couldn't send them a message. A friend showed me ICQ and I hated the concept; I thought "but if I go online and I see someone online there, isn't it like walking into a cafe and seeing them, it'd be rude to ignore them and not say hello?". I saw it as a virtual place where people can come and go and you have a chance o catch up.
Nowadays I can make anyone's phone ping and notify them that I want their attention using WhatsApp, etc within seconds of thinking it, and we've lost the concept of "Hey, fancy seeing you here! How have you been?". It seems connecting to anyone is possible 24/7, so it doesn't happen anymore.