Decentralized (to me) implies a lot of people working together on something, without a clear leader or headquarters. I think he was right to use 'fragmentation' ... a lot of the conversation is isolated and most likely redundant.

To use the obligatory p2p reference... the DHT peers in bittorrent are decentralized (no clear leader but all generally working together). Private trading groups on IRC are fragmented (they are isolated from each other).