What is scarce, however, is affordable housing. The problem with housing is indeed the artificially propped up prices which makes it impossible for people to buy new housing.

Btw, this does not counter the YIMBY argument, which argues that we can drop housing prices by making housing easier to build. Part of that would be by increasing supply. But another major part of the YIMBY argument is that if housing was easier to build, everytime a developer got an opportunity to build new housing stock in a desirable area, they wouldn't always need to go for the highest value, i.e. luxury housing, build. They could actually look at market needs and build affordable and/or starter housing.

Right now getting the right to build a property in desirable areas is a once in a decade opportunity, so they're willing to keep their built housing empty for many years, because they won't get a similar opportunity until much later, if ever.