The "raw data" in this case is my friends' lives. Based on my (off-Facebook) interactions with them I remain confident that Facebook does a good job of keeping me up to date on their lives when I use it.

i can tell you first hand that it does an awful job with my collection of facebook friends. it doesn't prioritise the people i care about most or even the things nearest to me... and more than once has absolutely polluted my feed with someone to the point i considered phoning them to explain why i was about to unfriend them.

i'm not saying your experience is untrue... just that facebook haven't done a great job of this for everyone at all.