Haha well I appreciate the upvote! I think you pose an interesting question. Also Viewing adds very simple feature and many sites choose implement it themselv

Haha well I appreciate the upvote! I think you pose an interesting question. Also Viewing adds very simple feature and many sites choose implement it themselves. I think it makes sense as a service because adding this feature usually requires setting up another server to handle the real-time connections. If you're building another Google Docs then the real-time communication is your core competancy, but if you're building a line of business CRUD Rails/Java/PHP app, then it's much simpler to add two lines of code and not worry about maintaining the additional infrastructure.