I think the fact that he cites work on a 'private social platform' is significant. Even if you set aside broader trends in consumer apps and just look at FB its

I think the fact that he cites work on a 'private social platform' is significant. Even if you set aside broader trends in consumer apps and just look at FB itself, this trend is inevitable given the way statuses--a prominent part of the Newsfeed--have been in decline for years, while Groups have been flourishing.