I can see the appeal of 1x for off road and am currently awaiting an 11/42 cassette for my fat bike. It has 2x 11/36 but loaded is a bit too hard to pedal up some steeper off road hills. If I were building for off road from the ground up I would include 1x.
The difference I find between bikepacking/off road and traditional touring is the frequency you shift to meet changing elevation. 1x makes that far more simpler. It's linear with out the need to consider when to bump up or down the chainrings which becomes a consideration with wide ratio cassettes. I've found I want the low end but don't really need the top end as much. The terrain usually doesn't facilitate flat out riding in that range. In the same vein, I have added a dropper post - something you rarely if ever need traditionally touring. Off road it's nice. 1x also facilitates placement of the dropper lever on the left.
Of course, the fly in the ointment is what people describe as gravel / touring conditions. Sometimes it's just a road with some pebbles on, other times it's a logging road.
