Entirely ignoring whether or not a monopsony is OK or a good thing, or the exact details of this situation - are there any retail book sellers organised as co-ops operated by authors or independent publishers themselves?
Even if the co-op doesn't actually do any of the technical side itself, and outsources that, they could easily retain control over the code and the customer base, which would be a good thing for them.
Even if the co-op doesn't actually do any of the technical side itself, and outsources that, they could easily retain control over the code and the customer base, which would be a good thing for them.