I agree with you that zoning is probably the most practical of the systemic issue that could be used to address affordability. Land use reform touches a lot of areas and can be used to reduce economic burdens that have to do with wage stagnation and rising cost of services, increase transportation costs, and other "capitalistic" pressures. If land is disproportionately expensive in desirable areas due to its access to work,services and the restrictions placed on new development. There's only two ways realistically that you can create housing that has a modicum of affordability. One is government intervention, either directly through things like subsidies or rent controls, etc or more indirectly like supporting community developments like the german "Baugruppen". Or through increasing the efficiency of the property though thing like upping its density, which before exclusionary zoning (direct government intervention through developer lobbying and community pressures) of the 1900s was just part of the natural growth of a city.