it would be OK if those who post these articles actually found them interesting but from what i have seen most of those who are posting a link to a blog or a news site are actually advertising that link and want to redirect some traffic to that place which as far as i can tell is not allowed since most of the times when i report a "link spam" they are removed.
Beyond the reasons to promote their sites, get more traffics, I guess there is another reason. By doing this, they try to do something they self-think as constructive and hope that their contributions (from copy & paste) will result in some awarded merits. Sometimes, I saw some users get some merits from that and maybe the others look at it and try to do the same. Over time, we see another epidemic of copy-paste-for-merit-hunting topics.