I guess some people find entertainment in that. I've seen people post right here on the disboard not so nice things about their relatives and neighbors. Stuff that would prob be just as hurtful to them, if they knew it was being posted (and surprised that someone would share the stuff they do). Sometimes it's so personal, with so many details, that that people on the board can figure out who is being talked about (my neighbor was able to figure out who a poster on the dis was talking about and was apalled that such personal info was posted on a board like this by that person). The big difference here is, the disboards let the mean stuff be erased, either by the person who posted such mean and hateful stuff (once they are called on it), or by moderators, where as on the walmart board, it's prob there to stay. I don't see much difference between the two.
That said, I'm always thankful when I'm not in the pictures on those sites LOL!
Obviously some people do. It still doesn't make it right. I don't like middle school behavior whether it occurs in middle school or online. Whether this is the same as certain postings on the disboards or not is open to debate (I happen to disagree with you, but that's not my point here) but it is wrong in any case.