Here's a pretty decent article from Fast Company titled "The Sharing Economy":
From the article:
"Amazon came first, then eBay, and peer-to-peer is next. It's almost as far as you can get on the spectrum of goods exchanged,"
That evolution (from a centralized model to a centralized+P2P hybrid model to finally a pure P2P model) is also described here in a post by Tim Hyer of RentCycle: http://blog.rentcycle.com/building-the-bridge-to-p2p
Specifically Tim describes that until eBay really took off, we as a society were too fearful of doing business P2P-style with strangers. Once that fear eased, Craigslist was able to dominate its market.
"It’s all about baby steps and doing what’s right at the appropriate time."