It is perhaps the case that students read less and so write worse than they did once. But having worked as a copy editor long ago, I can tell you that a lot of Ph.D.s wrote pretty damn badly before most of HN was born. (OK, Ph.D.s in the social sciences and E.D.s are mostly what I'm thinking of.)
And "Finally, the very act of employing, empowering, and often elevating such people [term employees] denigrates real scholars and scholarship by definition." I haven't heard of a lot of empowered adjuncts. And if that adjunct happens to have what it takes to teach freshman composition or an introductory survey course, I don't see the denigration. As for real scholarship, well, not everything published in a refereed journal is more than formally scholarship. One could, for example, compile an entertaining anthology of things that writers and highly qualified critics have said about Proceedings of the Modern Language Association.
Finally, what does a parent expect who sends a child off to school unable to write well and disinclined to read? It does seem to be a premise of US education that if you keep people in a classroom setting long enough then something will happen. But why should parents believe that?