This would function similarly to Twitter and Instagram’s collaboration features. At root, it would allow more than one user to publish a single post at once. With this feature, all users would receive all notifications associated with the respective post; that is, all of the accounts attached to the post as its publishers would be notified of incoming replies, likes, external hyperlinks, and all would receive badges as the post reaches the appropriate milestones.
This would especially be useful for charity posts. (See here for an example.) It would also be useful for posts of enlightenment, guidance, and uplifting. Last but not least, it would be useful for announcements; not those made by developers, but those made by players, such as giveaways.