If it were practical to mirror sci-hub and libgen, that would be one thing, but despite a lot of talk online I have yet to see a practical way to put my hands on such a thing.
We need the ability to circulate HDDs physically in a semi-organized fashion, samizdat-style.
Realistically only maybe 10% of that is actually useful, but reaching that 10% is gonna be very labour-intensive. You would have to do a lot of cleanup of different formats, duplicate uploads, different editions of the same book, scanned PDFs, and what not, while big players with their own ebook stores (Amazon, Google, Apple, any ebook store) already have all of the proper metadata, a common format to work with, and a lot less duplicates.