"Hacker News is a social news website focusing on computer science and entrepreneurship." [0]
It's the same as a group on any other system, just different formatting. It even has karma which can suck you in...
I do not disagree with the sentiment though, managing the amount of time one gives to social media is tough. Picking good social circles and getting out of bad ones is tough.
Yes, Hacker News has a 'share button'. I think what sets it apart from sites like Facebook is that it's not sufficient for the shared item to garner lots of attention; rather, it will be subject to written criticism, potentially leading to downvotes and flagging.
Finally, Hacker News is moderated by very thoughtful people, ruling out a big chunk of the content that makes unmoderated social media little better than a tabloid magazine.
That said, maybe the differences comes down to: are we being drawn in through manipulation to post beyond what we otherwise would have wanted to, for the benefit of others? To an extent, this is what karma is.
Now, who's fault is it for being drawn in more than I want to be? I take responsibility for it and also agnolage my weaknesses for distraction. Maybe you could equate social media to a liquor store. Fulfilling a demand, serving the community, and also praying on and enabling it, in a bad way.
Most of the time I'm distracted by social media, I would be better served by sleeping.