Collaborative writing : the future?

We are all, in the context of online media &  writing, familiar with guest blogging or guest writing. It is a basic form of collaborative writing. However, these days I see a new stream of media, purely based on collaborative writing coming up in a big way & influencing our lives online.

Update : I had started writing this post when I became a writer on Medium but I never got around to completing a post there. So, I never got around to completing this post either!