The article says it's a mystery but then nails it:
"In line with Google’s vision to organize the world’s information, the focus on Google+ seems to be shifting to content more than relationships. ... I wonder if Google is more interested in being Reddit (the front page of the Internet), than it is in being a Facebook/Twitter clone (what your friends are up to)."
"In line with Google’s vision to organize the world’s information, the focus on Google+ seems to be shifting to content more than relationships. ... I wonder if Google is more interested in being Reddit (the front page of the Internet), than it is in being a Facebook/Twitter clone (what your friends are up to)."