It can be argued that the original neo-Marxist philosophers from the 1930’s to the 1960’s fully intended the “articles of faith” that you rightly identify as inimical to the longevity of the faith, to be inimical to the longevity of western civilization, the point being that Communism “should” win the Cold War.
Well.. ..maybe. I’m not a deeply informed postmodernist historian, but it was my impression that the original ones considered both capitalism and communism to be “grand narratives” worthy of deconstruction.
As to what their intellectual tree has done since .. you may have a better point, but I still don’t think the intent of most of them is to destroy western civilization. They’re not evil, they just misguided utopian idealists who haven’t spent enough time critically deconstructing their own construction. And their analysis framework woefully under emphasizes stability as a positive societal trait.