Why do open access consortia affiliate themselves with questionable publishers The open access publishing world has a number of predatory publishers. Many know about Beall's list which identifies publishers and journals that engage in questionable practices. The existence of these questionable publishers and journals makes choosing a quality open access journal difficult. Consortia like the Open Access Scholarly Publishers Association and the Directory of Open Access Journals seem to promise a level of scrutiny. For example, members of OASPA include the Royal Society and PLoS and while I cannot find a link confirming it, it seems like the AIP is also a member. To me these are above the board legitimate and well respected publishers. There are also members, like Frontiers, that I am not sure how I feel about. I like that Frontiers is trying to push an innovative model of publishing, but I am not sure that I want them to have a large say in defining "good" open access publishing practices. Finally, there are members like MDPI which Beall classifies as predatory and Hindawi which while it never made Beall's list, did make his "watch list".

I think I have two questions. First, why do these consortia affiliate themselves with questionable publishers? Second, how can the academic community pressure open access consortia to consider their members carefully?
Why do these consortia affiliate themselves with questionable
  publishers?


Hindawi is a founding member of the OASPA and MDPI, whichever opinion we might have about the quality of its journals, is a major player in the OA business. The OASPA apparently conducted an internal investigation about MDPI and seem to be happy about the results. The question might be more: is the OASPA questionable?


  how can the academic community pressure open access consortia to
  consider their members carefully?


I would recommend not to consider open access consortia as relevant. Then, not submitting papers, not serving on the editorial board, and refusing reviewing tasks for sketchy journals.

On a more general level, one thing we could do is reduce the demand for low-quality, pay-for-publish 'OA' journals by challenging the hiring policies based on publication volume in our local institutions.