I don't think anybody should be posting names, or speculating about names of people they don't know personally in publicly posted photographs. I think anyone who was named has a reasonable basis for a lawsuit against the person who posted the name, and (depending on the details) if I was on the jury, they'd have a good chance of winning a case for defamation or emotional distress.
Publicly discussing the persons in the images themselves is bad enough. This will have a negative effect on those people, whether their names are given by Reddit or not. When you publicly point to a particular person and say that this person is suspicious, and may be the bomber, you can bet that this will have a negative effect (given the huge audience Reddit's speculations evidently had).
I honestly don't see anything wrong with such speculation, were it not for the fact that it's done in a very, very visible way. Among friends, playing detective is one thing. On publicly accessible and widely read sites on the internet, it's something else.
I think Reddit did many things right. They identified backpacks which could possibly have contained pressure cookers. They correctly identified the logos on the hats which is something the FBI either did not do or did not publish. I think they deserve credit for the things they did right as much as they deserve scorn for the things they did wrong.
The logo on the cap may or may not have been correct (seems it was correct, but who knows?) but it was predictably inconsequential. The odds that identifying a ball cap matters in this kind of investigation are vanishingly small.
The backpacks identified seem to have served no useful purpose, and caused harm by resulting in publicity regarding these poor, uninvolved people.
So, I'm afraid I don't see any particular good coming from Reddit -- at least, excepting the fact that
they caused such harm that they might have inadvertently had a good effect.
