People keep forgetting this. Google Reader was the best social network for academically minded people that I have ever been part of. As one blogger after it's shutdown said: it was a social network for people who don't want to talk about themselves
One usecase of RSS is, ahem, porn (yes that's part of life, especially Tumblr). That's a non-trivial usecase which is the reason why I donated to TheOldReader but refuse to pay a subscription; and RSS readers stubbornly trying to share my RSS reading on a social network was a risk for me.
That's a perfect way of phrasing why I think reader is the best social network Google ever made. Thank you.
What features were those?
The sharing of RSS feeds, and arguably even better: the bookmarklet to share any page on the internet