Thank you Droid. I think you put your finger on it. We're meant to laugh at the idea of using Stonehenge for bouldering - but that's only because a majority of people think it's more "fun" to treat it as a revered ancient monument. (I don't think bouldering would do much harm, actually, especially if no one used chalk.) In any case, Stonhenge has been heavily restored. 200 years ago, it looked very different. Quite a few of the stones have been re-erected after falling over, and some are set in concrete bases. The site has also been heavily excavated. Was that ok? Would using it for bouldering or SRT practice be less "damaging" or intrusive?
As for a via ferrata at Malham or Goredale: currently, the collective majority view seems to be that these are best preserved as places for rock climbing. But the crags are littered with bolts. Some have argued that this represents just as much a "desecration" as building a zipwire or via ferrata.
Once you dig into this subject, it all becomes a lot more problematic. And indeed, relative. I want to keep caves looking good because I'd like myself and also future cavers to continue to have "fun" in them, and the level of fun is greater if we preserve them. I also want us all to be safe, so I support good quality fixed rigging aids. Ie: lots of drilled holes and bits of metal in the rock.
And yes, Droid, we are on the same page.