Actually it does something kinda sorta similar with Facebook Pages and Groups. Especially now that lots of people write directly on their Pages instead of in a blog. You can "like" the page which is similar to following RSS.
Admittedly, this is a lot different, as Facebook decides what you see. You are not guaranteed to see all the postings and you can't "save them for later".
But it seems to work, at least for the bigger part of the population.
But it seems to work, at least for the bigger part of the population.