Because almost all independently published books sells almost no copies, so there would be no revenue stream. The lack of sales is not a knock at indie publishing: there are plenty of reasons to publish a book other than making money. But it makes it difficult for services to make money off of them unless their incremental costs are negligible.

From an author's perspective, the monthly charge seems problematic. Why pay someone a per-month charge for a book that you wrote last year? Much simpler and cheaper in the long run to generate an e-book using Sigil or similar, and put it up on Amazon for free.

I'm a lousy judge of business models but the intersection of people who would use a service called <em>git</em>-anything and people who aren't tech savvy enough to generate their own e-books or PDFs seems very small. Sigil in particular makes e-book creation trivial.

Comments here suggest people are using the service and pleased with it, but it seems very expensive for a relatively small increment in convenience.