By design. The left wants us to not be able to, and to actually shun, judging one course of action, behavior, or choice as being better than another.
Not quite true. Such a position would be value-neutral, which might have some actual value in teaching.
Their true position is invariably anti-American or anti-Western civ.
Kenya or Cuba or Sri Lanka or Iran are not portrayed as being equal to America, but rather as being inherently superior.
And all of a sudden, the US started diminishing the church, weakening our schools, coddling our under-achievers, embracing feminism, raising children the Dr Spock way, initiating a sexual revolution, and normalizing all kinds of anti-social behavior.
We are not the country we used to be. Militarily, we are still the tops. But in so many ways, we are a weakened, and broken nation. It's almost like their was a plan to bring us down from our position of awesome strength.