John Cochrane understands the elasticity of supply

Everyone is focused on building, but “supply” is so much more than building. There is tremendous supply in using more efficiently what we have now. Most cities have laws against renting parts of single family homes, or sharing larger homes. Think how many spare bedrooms are empty every night. There is plenty of housing supply in the US, it’s just not in places where people want to move. Others moving out is “supply,” and greatly impeded. Older people stay in too-big houses and apartments, in locations close to work and school opportunities that young families desire, but the older people no longer need. Why? If they sell, they are taxed on capital gains, even just due to inflation. They lose property tax exemptions, and, of course, rent control protection. Each older person who cashes in, downsizes, or moves to a more neighborhood more suited to them, supplies a house or apartment. The non-portable fixed rate 30 year mortgage, an invention of our federal housing subsidy regime, leads people to stay where they are rather than move to where they want to go, and free up a scarce house or condo for someone else. Strong apparently “consumer protection” laws in rental contracts dry up the supply, especially to the marginalized. If you can’t kick people out, you’re much more careful who you let in. Limits on short term rentals limit rentals. Remove rent controls, permanently, and houses and condos can be rented. Many houses and apartments need rehab, not new construction, which can happen very quickly once owners know they will not be robbed of their investment. Even “affordable” housing leads people to stay where they are, rather than move to better opportunities for them and free up an apartment for someone else, because it’s rationed with long waiting lists.

The rest of the post is an excellent analysis of rent control.  On one of John’s closing points, I should note I am not opposed to speculating about motivations.