The German critique of Pennsylvania Dutch reminded me of how the Nazis critiqued Yiddish back in the day for not being High German and thus its speakers must themselves be of lower class/value
Setting Nazis aside, Germans are used to having a single source of correct grammar and vocabulary.
The first Duden was published in 1880 and helped standardize German language a lot, even though local accents and dialects still persist. But speaking in dialect is considered somewhat low-brow in German language space, unless you are Swiss; even there, people will code-switch all the time.
(E.g. during class, both the professor and the students would speak High German, but during recess, they would switch to Swiss dialect.)
A rural language of peasants who do not use even old tech such as newspapers and radio and reside on a huge territory will necessarily diverge into a barely mutually intelligible family of local dialects, at least in the spoken form. Basically the Medieval or Early Modern standard situation.
The thing is: today (!) there is no such thing as a "german critique on Pennsylvania Dutch". Most germans aren't even aware that such a thing exists.
Also, this one citation is just anecdotal. You cannot conclude of any mainstream thinking about Pennsylvania Dutch. In the end, journalists often use items in their stories that create the highest emotions, not necessarily what reflects reality the most. So the writer of that citation might not have outright lied, but he might not reported about the general mindset about this.
Keep in mind that in 1780 germany itself was a mishmash, hundreds of counties, fiefdoms, kingdoms, self-governed city and what not. And even the language was much more a mishmash than today. Sure, Luther's work already started a bit a common way of writing. But we still didn't have some "high german" definition, e.g. no Duden. The Grimm Brothers, not only collectors of oral stories, were just 5 and 6 years old!
I guess during that time someone from Emden (very north-west) looked down at someone from Passau (very south-east) --- and the other way. Each one claiming that the other is uttering an unintelligible gibberish.
Oh, and EVEN today people from the center of Germany thing that speaking a strong german dialect (e.g. Bavarian, Swabian, Saxonian) correlates generally with low education / lower class. Because in THEIR region it is actually so. However, in Swabian it doesn't correlate. There was even the pun that in order to climb the carrier ranks at Mercedes or Porsche, one had to speak Swabian ...
The first Duden was published in 1880 and helped standardize German language a lot, even though local accents and dialects still persist. But speaking in dialect is considered somewhat low-brow in German language space, unless you are Swiss; even there, people will code-switch all the time.
(E.g. during class, both the professor and the students would speak High German, but during recess, they would switch to Swiss dialect.)
A rural language of peasants who do not use even old tech such as newspapers and radio and reside on a huge territory will necessarily diverge into a barely mutually intelligible family of local dialects, at least in the spoken form. Basically the Medieval or Early Modern standard situation.