Uh. Do you mean that, because a project is open source it has to limit itself to the lowest common denominator (not targeting git specifically here) rather than aspire to a better/more suited toolchain that its community believe in?

And by the community, I do not count those not having made any contribution but complaining about what is there in the first place.

This case is about the toolchain, but the same could be set about the code. Does it has to stick to an imperative form, as it is the most common widespread and understood paradigm, or can it be functional because it fits best the original design?

As long as the API is clean and the documentation is clear, I'm fine making the little extra effort to enter the world of the author rather than him/her lowering his/her expectation about what the project, as a whole, should be.