What I see in the article is that most of those fake papers were conference proceedings. Typically, submissions to conferences have a very low bar to publication.
The article also said that over 120 of these fake conference proceedings were published in five years. That’s a minuscule number compared to the millions of scientific publications every year. It is also a small subset of the 20,000 fraudulent papers estimated to be published every year.
Isn't that a problem in itself?