As I recall, he was actually talking about the 1700's, not the 1800's, and said that by the mid 1800's, that had already changed, if in fact it was ever as rosy as he painted it to be (I doubt that, as I studied political discourse during the period of 1779-1860 fairly extensively).

In that same book, he also argued that the telegraph enabled news without context. That hit most of the US market by the 1850's. Yellow journalism and the general sensationalist nature of news writing in the late 19th and early 20th century also don't support his argument about the written word's innate superiority to oral argument and television.