In a posting entitled Mandating OA via Paid Publisher-Archiving (PPA) versus Author Self-Archiving (ASA), Stevan Harnad states "If research institutions and funders have the spare cash to pay whatever publishers ask today for PPA without having to take it away from research allotments, then the outcome (100% OA) is welcome and optimal for all."
I'll comment on PPA in a moment, but let's first look at this extraordinary statement. It reduces science publishing entirely to an 'alms race'. Publishers stretching out their hands in the hope that some benevolent librarian or funder will throw in a few coins, thus enabling the publishers to go on publishing. It beggars belief, if this expression was ever appropriate to use. What a way to sustain the formal peer-reviewed journal literature! The formal peer-reviewed journal literature is clearly worth very little. In his view.
Those with a 'harnadian' inclination should really not bother publishers at all with their articles. They should just 'archive' (read 'publish') them in some repository and move on. Shame the articles can't be labelled as having been published in a peer-reviewed journal, which would make them more valuable and be noticed and taken seriously, but hey, everybody can see them and the publishers just haven't been able to beg enough cash to publish them.
For those who do think that there is something of value in having a system of journals in which the peer-reviewed scientific literature is formally published, it is probably worth looking for more robust ways of economically sustaining them than just scrambling for alms.
Subscriptions, on the whole, currently sustain the journal system. But they have a downside. They do not, by definition, provide open access. So that's why new publishing models have emerged that do.
Unfortunately, Stevan derisorily calls these new publishing models PPA, for 'Paid Publisher-Archiving'. As if 'archiving' is what publishers do. Nobody pays a publisher for archiving and no publisher asks for payment for archiving. Publishers ask for payment for having an article peer-reviewed and formally published in a reputable journal. By having an article peer-reviewed and formally published in a reputable journal, it becomes worth a lot more than if it were just self-published. Worth a lot more to the author (or would some informally published article be seen in the same light by your tenure committee as one that's published in a journal with an impact factor?), worth a lot more to the reader (or would a citation to some informally published article be taken as seriously as one that's published in a journal with an impact factor?), worth a lot more to the funder, worth a lot more to science, and worth a lot more to society at large. If that were not the case, why should authors want to publish in journals? Why should funders and institutions expect (read: require) them to? Why should fellow scientists be keen to know where an article is published? Because there is no value in the formal peer-reviewed journal publishing system?
If there is value in the system, however, it needs to be properly sustained. Not with alms.