I don't think that non-linguists quite understand how infuriating these little pronouncements by non-specialists are. Especially after they begin to pile up like dirty snow in the winter. If I were to write a book about computer graphics programming and inserted a small paragraph or page or two in it about art history, in which I dismissed the Flemish School of paintings as a vulgar misinterpretation of the Italian Renaissance, and which led directly to the degeneracy of van Gogh and Gauguin as well as the French Impressionists. You might imagine that art historians and even some artists might disagree with me.
Barzun is just one in a long line of people who have achieved prowess in one field (in his case literary history, criticism) who thinks it grants them the right to pontificate on matters linguistic. In fact, I grant that he has that right, but I and others don't have to take his half-baked, crackpot theories of the doom of English seriously, mainly because other non-linguists have said the same and never offered any proof. In fact, they have usually made the same mistakes over and over again when complaining about the same, tired old tropes.
