>algorithmic timelines telling me what happened while I was gone (trust me, twitter...I would have gotten to it eventually), prioritizing what shows up (trust me facebook, I do a very good job hiding content on my own)

Absolutely! At least give me an option (even if it is buried nineteen pages beneath about:config) to switch to a simplified reverse chronological stream. Until this happens, I've in followed everyone on Facebook. If you didn't send something specifically to me, then no I definitely didn't see it. (: