You could say the same thing happened or is happening with Twitter. They started with the “while you were away” feature and it needs to progress similarly to Facebook’s “definitely interested in X”. Granted using twitter you can get all the tweets of a person via SMS. One of the biggest problems facing social media is considering those individuals who are not hyper active and giving them the curated content that brought them there. For Medium, maybe that is via the ability to favorite individuals and having a favorites stream that includes the occasional “similar to X whom you favorited” post. It is just a matter of time. It’s our job to be vocal about what we want to accelerate that process.