Thanks for the discussion! Maybe this should discussed in a broader manner within the OSM community. To me this looks like a significant change in tagging strategy. Is there already some thread in a forum on community.openstreetmap.org?

But please don't get me wrong! I am fully open to new ideas and approaches but I think this should be discussed within the community. I should also mention that I do not consider myself to be an OSM expert.

My 2cent:
I consider myself being an climbing expert in Hochschwab region (repeated more than 60 different routes and did a few first ascents). And yes it is the case that (almost) all faces have established climbing routes along with topos. To my knowledge, there are four guidebooks available  (latest was released 2020) and also some guidebooks having selected climbs of this area. So we speak about 500 to 1000 routes. I am not sure if OSM the best database to document this, especially for alpine style routes like we discuss here. Typically, they are in vertical direction, while OSM is more focused on horizontal data :-). Tagging each face with sport=climbing does not bring any valuable information in my opinion.