Welcome to the forum.
I strongly support this. The classification primary. secondary, tertiary, unclassified, residential is derived from the function of the highway for the traffic and not from the condition. In a populated area (settlement) the highways are residential or higher classified independent of the surface or if they are planned or “naturally grown” by usage. Even in developed countries many highways still follow former footpathes or tracks and thus are “naturally grown”.
According to wikipedia: Angola transport 25% (19,156 of 76,626 km) of highway are paved. I think it’s no good idea to tag the other 75% as highway=track.