Maybe that's true, and it certainly adds a convincing back-to-the-garden, unwashed ambience to the psychedelic rock proceedings, which are mostly appealing, although sometimes a little obtuse.
And, yeah, the conga drums and flute twittering of the opening cut "Everybody Daylight" could have been recorded off the grid, but you'd need electricity for the minimalist slide guitar and lovely R&B electric piano and organ, not to mention the recording equipment. I guess anyone with a pickup and a few gallons of gas can schlep a generator anywhere, though.
So it's possible that Brightblack Morning Light is in essence a field recording, for which Nathan Shineywater and Rachael Hughes acted as their own Alan Lomax, capturing raw on tape the musical essence of their spooky mélange of back-country blues, artsy drone and funky, dub-like head trips.
The combination feels unsettling and alien, but in a good way--the same way that Beck plays hip-hop and Devendra Banhart plays folk-rock, like outsiders instinctually connecting to the inside groove without over-thinking their own intentions.