No, that was meant to be covered by highway=two_wheel (desperately in need of a better name).
However, how is that not redefining highway=path, which is a nogo, as this post History of proposals to fix highway=path ambiguity – and a wayforward? - #3 by Langlaeufer and the number of its likes seem to suggest?
Precisely because I read those (and not only) I wrote that post. Though one can hardly ever read enough.
The main benefit would be general-purpose (i.e. not hiking oriented) routers stop sending people to places where majority public does not see anything resembling a way. The purpose would not be to add information but to affect routers, this being a feature and not a bug.
It means it is not anything more difficult than hiking, which is tremendeously useful, actually.
People definitely do that. It is even in a dictionnary with that precise usage: https://dictionary.cambridge.org/dictionary/english/scramble
Well, you could have highway=notpath or highway=notapath if you wanted to be language purist, however under your Classification section, you have adjectives so I do not think this is a problem in practice. (Otherwise I think your post is really good and should not just stay burried in the forum).
This is not really for this thread, but I would like to see some pictures for this to have a better idea what these are. They sound potentially useful though!
Frankly I think path now is too broad for this to be useful (and it would clash with existing schemes like sac_scale).