What these proposals seem to have in common is that because highway=path is considered too “general”, they move detail from a lower-level tag up to the key value or even the key itself (by splitting off pathway=* from highway=*).
Looking at the “bad” end of highway=path, highway=scramble and highway=mountaineering are adding the detail “this is a difficult path” to highway=path that highway=path + sac_scale=* can tell in much more detail (6 and hopefully soon 7 levels of detail). This thread similarly proposed new tags for pathless paths to express what highway=path + trail_visibility=no is also expressing.
When we try to express such information in first level tag values, we loose detail; if we want to prevent loosing that detail, we would have to introduce many more tag values. What would you call a path that’s quite difficult and not very visible, that you could also tag with highway=path + sac_scale=demanding_mountain_hiking + trail_visibility=intermediate? We would need 7*6=42 different first level tag values to express the same detail that highway=path + sac_scale=* + trail_visibility=* can. And we would need to survey the path and decide on its difficulty and visibility first before we can map it.
I don’t think we should go this way.