I don't think OP was referring to any social features beyond what RSS specified:
> In retrospect, it was the least toxic social network. You added your friends, their recommendations bubbled up in the interface, so you saw cool new stuff.
This is just "subscribe to people's blogs". That's still the ideal social media for me.
No, Google Reader had a social layer where you could add friends, see items that they recommended, and comment on them. It was really great, but it was ruined by the migration to Google+ before Reader was actually killed.
My friends and I loved Buzz and lamented its loss. We tried Google+, but it couldn't even really do what Buzz could do, and it certainly didn't have any other killer features, so it didn't take.
> In retrospect, it was the least toxic social network. You added your friends, their recommendations bubbled up in the interface, so you saw cool new stuff.
This is just "subscribe to people's blogs". That's still the ideal social media for me.