There is nothing new about maintaining mountain trails, there are many examples in the Lake District and Penines where roads have been maintained for at least 2000 years. Packhorse trails also exist from the middle ages consisting of slabs of local rock forming a simple pathway. During my activation of Stony Cove Pike yesterday I saw perhaps 20 “dumpy bags” of rough stones that had been air lifted to be used to maintain a very popular path over boggy ground.
Regarding erosion, one of the worst examples I have recently seen was the scar perhaps 100ft wide by 200ft high, west of Scale Force in Buttermere. Here water ingress from the horizontal path caused a burst of the fragile turf and a large eyesore necessitating a path deviation.
Maintenance is a necessary evil (and cost).