This started 50 / 60 years ago. The “grievance” industry is applied postmodernism. It’s been feeding and snowballing over decades. The internet and social media threw gas on the fire. The Democrats decided to take up the mantle of social justice because they perceive it as a way to gain power.
Ultimately it is a denial of truth itself, a denial of objectivity.
It started with the left, continues on the left, and has its formal representation in the Democrat party.