There's no such thing as affordable housing[0]. Just housing. You can certainly argue that building a house is too expensive -- and due to NIMBYism, discriminatory policies, and anti-density regulatory environments, this is often true -- but affordability is not an intrinsic value of a building, and the problem is generally that housing stock simply doesn't keep up with demand in places which demand lots of housing (e.g., San Francisco, Seattle, NYC, London, etc.).
0. https://www.strongtowns.org/journal/2023/1/3/theres-no-such-...