I agree in parts. I know Walkhighlands (great, but not a part of the "wikiverse", so if the people running it, decide to close down, it's gone), Wikiloc (great, some tracks are private expeditions and not possible to reproduce, they have a "to pay for" premium membership), Outdooractive (was fine, but now full acess only for paying members) - so I know them, but maybe not the average user on OSM projects.
I checked the documentation which is different in german and english language, now I know what you are referring to (exists only in english variant):
"Routes that are suitable for inclusion in OSM should usually match one or more of the following guidelines: - The route is signed or otherwise identifiable on the ground....
You don't find this in the German version of the same page ;-(
But there are other criteria mentionned:
" - The route is established, documented and/or maintained by an organization that is well known or officially responsible for this function (e.g. mountaineering clubs, tourism boards, ...).
- The route itself is shared common knowledge among a significant number of people...."
So I think, the standard access routes to Munroes and well known hills should warrant a OSM route.
Even more if there is a signpost or map at the start, nothing is said about in which distances you must find waymarkers on the ground, and even for well known long distance trails, there are partly ruined or inexisting "on the ground", so the E4 in Cyprus, but that should not be deleted from OSM only because of the markers are rusty or destroyed.
Many trails in Italy or Cyprus even in well known Nature Reserves are only documented as Gogle Maps satellite images with a wide red line, this can be done better, even better if you have been there searching the trail...
But maybe we should delete the RW number, as they only relate to this hiking guide which is very popular in the german speaking countries, but is no official numbering and in fact is not marked locally. 