Social Justice is found in ever version of socialism. It is all based on Marx's need to create a oppressor class and and oppressed class. Without that duality Marxism cannot exist. Social justice is the idea of making the oppressors pay for their sins against the oppressed.
Stalin, Lenin, Mao, Castro, Hitler and Mussolini all preached making one group of people pay for what they allegedly did to another group of people.
Back in the later 1920's and early 1930's, the American Nazi party published a newspaper named, Social Justice. This was back when the Progressives had no problem pontificating on the greatness of Hitler, Mussolini, Stalin and Lenin.
The major problem with pushing the oppressed/oppressor narrative in America is we were never founded on that model. Yes, we had slaves in the early history but we rectified that. Then we had Jim Crow and that too is gone. The only group of people in today's society that are seeing the worst kind of oppression are unborn babies. They are being slaughtered in numbers greater than the holocaust and the left is leading the charge against human life that they find inconvenient. Of all of the sins that has been committed in this nation, abortion is the greatest. Far worse than slavery, the genocide of native Americans and any kind of mistreatment of any other group of people.
Because there is not an oppressor class, oppression has been redefined as opposition. If your a leftist and someone opposes your viewpoint then you win the prize of victimhood and you get to claim to be oppressed. You're not oppressed, we just disagree with your solution, not the intended outcome of your solution. We want to keep the government out of all of the solutions because they are extremely inefficient and wasteful.
Well... I'm just rambling on. I'll shut up now.