Indeed, if the idea of "the historical winners are the morally justified side" really screws over a lot of people. Just to take an easy example, the Native Americans. Their culture was decimated and, even left on their own for another thousand years, could never be rebuilt. They lost, big time. However, you could make a solid argument that their loss was a historical inevitability based on their level of technology and the structure of their society. It was a culture that was simply not sustainable. They literally WERE on the wrong side of history.
So, SJWs... let's talk about those Native Americans. Were they actually just "on the wrong side of history", or were they victims of an oppressive culture taking what it wanted from another group? Because, if you're going to use one argument as a moral high ground, you lose the luxury of having the opposite argument at your disposal.