Jeffrey,
The “Frontiers” journals in my field, such as Frontiers in Genetics and Frontiers in Plant Biology, publish legitimate research by the same authors that publish in the well-established, traditional journals. Yes, they are expensive, but so are the PLoS and BMC journals. Open Access is expensive in the hybrid journals, too. I am a review editor for a Frontiers journal. We are told that there is an expectation to publish in the journal occasionally, but that is the same for an editor in any journal; they are expected to publish in the journal occasionally.
In regard to: “Frontiers is known for its strange marketing, recruiting thousands of editors and editorial board members who are charged with drumming up business for the company, much like Amway.” I think this is one way to look at it, although it seems like a misunderstanding of what Frontiers is trying to accomplish. The topic section editors are volunteers who choose a topic and then try to assemble several to dozens of articles about that topic. The authors can be contacted by the editor, or they can voluntarily submit an article. To me, this is no different from putting together a session at a research conference in that the organizer of the session contacts potential speakers. Would you say that the organizer is “charged with drumming up business” for the conference? Much unlike Amway, there is no financial incentive for topic editors, they do not get paid for recruiting authors.
I really appreciate your service of identifying Open Access predatory publishers and journals. I hope your work does not evolve into putting all Open Access journals into this category.