[mcantelon]

Driving the adoption of identity politics seems to be a synergy between the Western ruling class's interests and those of a subset of leftists. My guess is the ruling class likes the ideology, and supports it, because it provides a moral pretext for weakening historically dominant demographics. Once these demographics are sufficiently cowed, they will be more willing to let go of self-determination and accept supernational rule (rule imposed by the EU on European nations, for example).