I suspect it's taking a while because when they do screenshots they're going to do it right. Just as with videos you save with "Xbox record that", I'm sure screenshots will be automatically uploaded to their servers and shared on your activity feed with friends.
This just comes off as excuse making for Sony. They were criticized for the PS3's lack of OS features for years. They chose to keep the OS dev team locked away in Japan and very little has changed. A YEAR after the PS4 launch and they still don't have some very basic features working.
I think the SharePlay feature is going to be cool for about two minutes after people try it, and go "wow, there is a lot of input lag doing this. Kinda hard to play this game being streamed halfway across the country".
Quick to call out features missing on PS4 and quick to defend features missing on Xbox.