But the thing is, the really major and important thing in this discussion, is that people don't do it to classic rock routes. It is well established etiquette in the climbing community, emphasised in guide books, passed on by word of mouth and heavily delineated on the BMC and MCofS websites that there are places where it is acceptable (specified tatty old quarries) and places where it isn't (normal climbing venues). So quite hard to miss really. Those that do it are fairly quickly informed of what is considered acceptable. I bet you won't find a single axe mark or crampon scratch on Right wall, Knights move, Peapod, Moonraker, Dream of White Horses, etc.
Scars from gear placement, polish and erosion from feet and unsightly chalk from hands yes, but tool marks? No.
Go and look at Rubicon wall, The Roaches, Bowden doors, Avon Gorge or any other popular crag and tell me whether the things that make the routes look defaced and obviously a climbing venue is due to dry tooling or general rock climbing.
And the number of people who dry tool is minimal. Really minimal. Probably in the "0.1% of climbers or less" realm. Most climbers don't winter climb, let alone indulge in the more esoteric aspects of the sport.
So to spell out UK dry tooling as practiced by the vast majority in biking language:
Imagine someone did some skids down that tatty bit of trail that you don't ride because it doesn't go anywhere and is behind the old factory where people dump washing machines, leave burnt out cars and is covered in dog turds. That is the equivalent of UK dry tooling venues. Believe me, I've been to many of them and they aren't places you want to be after dark when the denizens emerge. Hardly AoONB.