How did postmodernism dominate so quickly?

I continue to be amazed at how something as insane as postmodernism could dominate the academic world so quickly. The postmodern idea that everything is socially constructed (but not postmodernism?) is almost psychotic.

This has led to such bizarre things as transgenderism being promoted as natural, even if it requires years of extensive, painful and expensive surgery. It has also led to the overall destruction of standards of excellence in education with affirmative action, which overlooks the reality that we can't have both excellence and equality at the same time (as Clyde Wilson pointed out in Chronicles).

The only explanation that seems plausible to me for this freakish victory of postmodernism in the academic world is that the Nietzschean relativism and power philosophy of postmodernism was not successfully countered by the academic traditional conservative Christians, because they could not fully accept their best defense of the broadly biological origin of social behavior, taught by the scientific synthesis of sociobiology. Traditionalism could not affirm religion as essentially having been a better way to socially bond groups together for successful survival and reproduction. They could not see beyond their definition of God as being outside the world of power and material desires, and postmodernism won the academic war between Nietzsche and religion.

Readers of this blog know that the religious philosophy of theological materialism and the Twofold Path affirm the sociobiological perspective, which is seen in the evolution of the material world to supermaterial Godhood. The symbolic experience of the traditional Inward God is transformed into real Outward Godhood attained in material/supermaterial evolution. This counters both Nietzsche and postmodernism.