Population isn’t static. We need housing supply to be responsive to changes in demographics and preferences. If the towns no one wanted to live in anymore were

Population isn’t static. We need housing supply to be responsive to changes in demographics and preferences. If the towns no one wanted to live in anymore were 100% occupied, that would be very bad! It would mean more people were stuck. If the cities people want to live in were 100% occupied, that would also be very bad! It would mean there’s no such thing as a move-in ready home to terminate your search. You’d only be able to move by swapping with someone, or else everyone in the connected component of moves would need to move on the same day (some cities actually used to do that). In general, vacancy is good for buyers and tenants; it gives them both liquidity and leverage over sellers and landlords.