Within hours of Vine’s launch, the ability for users to find Facebook friends also using Vine disappeared. The move was not unlike a decision Twitter made in July to prevent Instagram users from continuing to find contacts using Twitter.
In a post on its Developer Blog, Facebook clarifies some of its platform policies. While not mentioning Vine by name, it’s clear this is the app the company is referring to when it writes:
For a much smaller number of apps that are using Facebook to either replicate our functionality or bootstrap their growth in a way that creates little value for people on Facebook, such as not providing users an easy way to share back to Facebook, we’ve had policies against this that we are further clarifying today
For more info: http://goo.gl/CZTyk