In the meantime I see how GP post was ambiguous and led to your rectification: he was writing as it's his own words, but in fact was paraphrasing the book series we're talking about [0]. But whatever it's GP or book authors' viewpoint, you are right to point out the logical fallacy. However I mostly disagree with this:
> there is also no value in making sweeping generalizations.
Those book series use this kind of generalization everywhere. You may argue those sentences are false - ok, but they still have a tremendous value: help the reader with their goal! One of the fondation of that method is the use of those sentence and in a sense (with extreme words) it's a brainwashing with false informations. But a very useful brainwashing that readers engage themselves consciously.
Also on a more linguistic side: people make generalizations everywhere to simplify the communication (Dogs are nice - Python versions management is always a pain - The internet has made everyone more connected...) and it often don't bother readers. But that's not the point here I guess.
0: just one exemple but there's plenty in every chapters, but I like this one because it's very factually debatable : > porn provides no genuine pleasure or crutch and you aren’t making a sacrifice. There’s nothing to give up[...]