Facebook activism, as defined by the article, has two purposes. First, it makes the person feel better about themselves. Second, it (presumably) improves their reputation among their circle of friends. The issues they are trying to raise awareness about are quite irrelevant. In fact, the person might be actively harming the cause they are trying to champion, because they are giving others the impression that sharing their post actually accomplishes something worthwhile, and might scratch their itch to actually act.