It is human nature to believe that we are "better than average" at things that it is hard to really calculate a ranking on. Spouse, friend, driver, etc are just good examples. Like Lake Woebegone, where all the children are above average, we find it comfortable to believe the same about many things -- morality just being one.
Just as wheels, gears and eventually engines allowed us to move faster and farther, modern internet tooling allows us to display our sense of moral outrage and whatever we want, whenever we want, making us feel very superior indeed.
So the technology makes is much easier to show moral outrage and become a "moral grandstander":
The world isn’t really getting worse. But people have incentives to act like it is. New technologies give virtually anyone, at any given moment, a platform to express anger. These new ways of communication, from Twitter to Facebook, allow anyone to express outrage at the newest political dust-up or celebrity gaffe. And by expressing anger in this way, people are able to communicate something about themselves – that they are morally sensitive, that they care about injustice – so much so that they are willing to accept the cost of being upset to show it.
Here is the basic idea. Grandstanders use talk about justice, rights or morality in general to show that they are good people. Grandstanders want others to think that they care more about justice, or empathize more deeply with the poor, or more clearly understand the plight of the factory worker than the average person. Some are more modest, and just want to show that they are on the right side of history. For grandstanders, moral and political discourse is a vanity project.PRACTICING Christianity is a great fix to this (pretending to be a Christian is not). A practicing Christian gets to admit that they are a crummy sinner, deserving of eternal punishment, and beg for the Grace and Blood of Christ in order to cover their awful sins everytime they take Communion.
Other ways to temper our natural bent for seeing ourselves as "above average" or even "superior" would be philosophy, literature, or even better, regular CIVIL discussions with people who are roughly as intelligent and well-informed as we are, but are of "the other" moral tribe.
In such discussions, "status" is gained being calm and civil, and display of umbrage is NOT a signal of morality, but rather a signal of a lack of maturity. If our nation seeks to stave off a nasty divorce that we seem headed toward, such discussions are the only likely way back to being one nation.