My criticism is on the authors of the articles, not on the HN voters. If the headline reads "Facebook blocks Tor, putting activists at risk", that's quite a damning claim. Maybe they author should check with Facebook. The commentors here at HN saying "it doesn't surprise me that Facebook doesn't care about activists" might not be constructive, but I'm not criticizing it because it's a forum like you said.
I'm not sure I agree that these things necessarily needed to be brought up on HN in order for them to be corrected. Just reaching out to FB may have done it. The author did not do this, instead issuing a retraction after the fact. Did anyone contact the MySQL team to see if this was a mistake before lighting the torches and grabbing the pitchforks?
The problem isn't the people here on HN. The problem is the authors of these irresponsible articles; authors who know that the more sensationalist of headline they write, the more likely the community will join their frenzy without question. It's meta on the tech journalist community, not the HN community.