So, where is the problem, some may ask?
These downhill races commonly get marked “highway=path; bicycle=designated; foot=no”. That makes them cycleways in the strictest sense, same class as those. The only difference being presence of an mtb:scale>0 tag.
All of the renderers available from the openstreetmap website will show them the same as bike paths. Some of the routers available on the openstreetmap website will treat them the same as bike paths.
Some other renderers even paint them as a white line with blue casing. Something that map readers accustomed to local map signatures will naturally interpret as a 2+m wide paved road. I asked the German map style producers to consider mtb:scale. They denied, what is mapped like a cycleway will get shown as a cycleway. This reminds me on the quest on the OSM-Carto issue tracker to show higher sac_scale paths differently. At least, OSM-Carto does not show paths as a white line with reddish casing. Some very prominent renderers do. So browsing my local area from them I see roads running up every other summit, where there are in fact difficult-alpine-hikes, in OSM terms. Shall I be fine and call them crap consumers? That might certainly make me feel more comfortable.