but when walking I used to dispose of banana skins or orange peel by tucking them into the dark crevasses of dry stone walls or under rocks
So it was you! The number of summit cairns I have taken apart and rebuilt to remove the tons of rubbish in them. Not only does orange peel take seven years to rot away in the hills, there is still the visual impact. Why should people have to sit around in other people's waste while is slowly rots?
There is much more discussion about waste and rubbish in the outdoors in the States than there is here. They have very different waste strategies for 'human waste' depending on the climate and the popularity of the area. In high use camping areas, like on sand bars on rafting rivers, nothing is allowed to be left behind at all. Everything, and I mean everything, had to be packed out.
In warm forested areas, burying human waste (but not toilet paper) is allowed in the active humus layer, but on high Alpine environments, in very remote areas above the tree line, they recommended smearing the 'waste' as thinly as possible over the south facing sides of boulders and rocks. Within a few days the light and sun had reduced it to dust, whereas burying it in an inactive cold soil layer would only preserve it.
They have even built 'composting toilets' in remote parts of the back country where unusually high numbers of people might camp, such as on junctions on long distance trails. These are often well hidden in sympathetically built rustic structures. I think there is a case for similar ideas to be tried here. One at say Sprinkling Tarn, Fords of Avon or Corrour Bothy might be preferable to walking passed endless small boulders with the tell tale sign of toilet paper peaking out from underneath.