I think this is somewhat questionable. California recently passed the laws to open the floodgates, so we'll soon be seeing how this plays out in reality. The points I've seen are:
* Modern requirements means building an ADU cost hundreds of thousands of dollars (at least here in CA).
* ADU significantly increase property value, and loan/insurance requirements are tougher for rental properties, making ownership harder.
* ADUs are rentals, which are 100% loss for the occupants. Building affordable condos would do much better at helping people build wealth. ADUs drive gentrification, from the point above, making ownership harder.
* Modern requirements means building an ADU cost hundreds of thousands of dollars (at least here in CA).
* ADU significantly increase property value, and loan/insurance requirements are tougher for rental properties, making ownership harder.
* ADUs are rentals, which are 100% loss for the occupants. Building affordable condos would do much better at helping people build wealth. ADUs drive gentrification, from the point above, making ownership harder.