And having a derailleur break that way to me sounds like a one-off occurrence that nobody could predict. I have not had that kind of problem since the mid 1980s when a bolt on a early 1960s Campy Gran Sport derailleur decided to unthread itself from the rest of the derailleur while I was in the middle of a century.
You're right, bikes in general are reliable, even so the the Rohloff is phenomenally so. I've had mine since 2004 and it's done at least 70,000 miles, in that time I've had two roadside issues - A broken female connector which was an easy bodge but wouldn't have made it unridable if not. And a broken flange, which after removing the flapping spoke I continued to ride. Over the same time period, my two derailleur bikes (Which between them do less than a third of the Rohloff's mileage) have had rides cut short three times including this one - the other two were, failed Shimano freehub and seized R/H Ergo shifter.
What bike would you use for that type of riding that has a Rohloff?
it's currently in a Mercury, though the same hub has Audaxed in other guises, originally a Raven tour and a custom Ti frame between that and the Merc.
This one - I may have posted the photo before ;) Taken at the half way point on the Skeggy 300 Audax a few weeks ago
(https://farm1.staticflickr.com/873/41428664362_ed908d8133.jpg) (https://flic.kr/p/267UJyA)
Sutton (https://flic.kr/p/267UJyA) by Paul (https://www.flickr.com/photos/phbike/), on Flickr