I agree with this point, and that’s why I’m definitely in favor of the postal address for addr:city. I mostly feel this because it’s very necessary in my area: within the City of Los Angeles there are a variety of ‘postal cities’ that do not correspond to government boundaries, but which may repeat addresses between them. For instance, both Way: 427942818 | OpenStreetMap and Node: Off the Wall Art Designs (10863489700) | OpenStreetMap are within the city boundaries of Los Angeles and have the address 319 West 6th Street, but one has postal city ‘Los Angeles’ while the other has postal city ‘San Pedro’, as reflected in the current addr:city tags. Tagging the San Pedro address as addr:city=Los Angeles, or even really some alt tag, would be very confusing, and IMO strictly wrong. Both nodes’ location within Los Angeles city boundaries can be inferred from geometry, so I don’t see why a separate addr:city and contact:city tagging is necessary. Just for reference, a local in the latter location would say they were in San Pedro, but would probably know that they were also within the City of Los Angeles.
Perhaps this is a tangent though, since I have no idea what the ‘911 addresses’ of these places are.