Your argument is for the equivalent of new Indian reservations. The poor people moving into these houses will tend to be ethnic or racial minorities. There will be no jobs in that area, and no access to transportation, and definitely food deserts, and no education, etc etc etc etc [include an 'etc' for every service needed for a population of humans in a modern western society]. It will be harder for people to live, and the neighborhoods therein would crumble from a lack of access to important resources.

The other thing the argument does is assume we have an "expensive land" problem. We don't. In most cases it's construction costs that are unacceptably high, not land costs.

In Philly and Baltimore, the situation is the same as described in the article. The estimates for building new low cost housing are up to 10 times the cost for private development, so it does not get built - and the land goes back to private developers, and sold to the wealthy. This has been a constant issue for as long as I have lived in these cities.