After reading yet another news article about predatory journals/conferences and how they weigh on the finances of labs in some countries, I started to wonder the following. Were they widespread before publishers of reputable journals started introducing the model where the author pays to have their paper open-access, the so-called "gold open access" (a name I dislike very much, but that's not the point)?
Indeed, I would expect that before that (which seems to be a relatively recent development, maybe less than 10-15 years ago...?), labs would have been much more reluctant to pay for the publication in a predatory journal, because that would have been a surefire way of telling that the journal was junk. And if a researcher had to pay from their own pocket, then I would expect the practice to be much less common, simply because fewer people could afford it.