No, but fragmentation with respect to single individuals is devestating. Do I send someone an IM, an e-mail, a Twitter DM, a phone call, a voicemail, an InMail,

No, but fragmentation with respect to single individuals is devestating. Do I send someone an IM, an e-mail, a Twitter DM, a phone call, a voicemail, an InMail, a FB message or poke, a letter, a buzz or what? If I have confidence that the target of my communications will notice my message regardless, then that is a feature to me. Moreover, if I want to follow a friend of mine, then I rarely want to setup and maintain another account, as is often required these days. Within a given social network, there's lots of room for clique-forming. There's even room for fragmentation between networks, so long as communication between networks can happen in a relatively transparent fashion.