It also makes an important point that might explain some of this - the part about how such conflicts about subtle 'microaggressions' are occurring in environments where there is already a high level of equality. In environments where minorities (of whatever nature) are only grudgingly tolerated and suffer significant discrimination, they may not be empowered enough to stand up for themselves and engage in such conflicts. But more importantly, if they look back and see an even worse situation in the past, they may be genuinely satisfied with their progress and not even want to protest or argue, getting upset with those who rock the boat. In the end so much depends on what you're used to and what you're comparing to - and millennials just have different standards and different points of comparison than older generations.