For what it’s worth, this explanation puts a lot of the blame on the word “road”, but the confusion is not intrinsic to this word. The reason for the confusion is that highway=road was redefined in 2016 (also in the main map features table). By then, data consumers like OSM Carto and Mapbox had already been interpreting it for years according to the approved definition that only encompassed what (English-speaking) laypeople consider to be roads, not primitive paths. (The proposal is literally titled “Generic road”.)
I don’t know if this change was accompanied by any discussion or outreach to software developers. But even if this was a stealth edit, enough time has passed that the new definition has apparently gained some traction. 