Even before 2020, the U.S. faced an acute housing affordability crisis. The COVID-19 pandemic made it a whole lot worse after millions of people who lost their jobs fell behind on rent. While eviction bans forestalled mass homelessness—and emergency rental assistance has helped some—most moratoriums have now been lifted, putting a lot of people at risk of losing their homes.

One solution pushed by the White House, state and local lawmakers and many others is to increase the supply of affordable housing, such as by reforming…