Before I started long-distance cycing, I grew up in mountaineering where it is common practise for guide books to start the description of a route with an overall grade, followed by a technical grading for distinct sections. The overall grade is usually a classification from Easy to Extremely Difficult in 5-6 steps. I believe that such a grading system would be very useful for bikepacking routes too.
Of course, not all aspects apply equally well. In mountain climbing, if you are not able to climb the crux of a route, you simply should not try it. Hence the technical difficulty of the crux is mostly a defining factor that goes heavily into the overall grade. I don't think that applies for many MTB routes with the exception of very technical descents, rare in bikepacking. Exposure to life-threatening factors, such as rotten rocks, seracs and extreme altitude, is also less relevant in bikepacking. What should go into the overall grading besides road quality and sustained high gradients is remoteness and absence of water sources. I am very pleased that Bikepacking Roots is developing such a grading system, see
www.bikepackingroots.org/bpr-route-rating-scale.html. I am very interested to see how it works out for their new Wild West route.