I'm a good bleeding heart commie so I'm all for doing whatever is politically possible to help poor people, but Philly doesn't actually have an affordable housing problem. There's plenty of affordable housing. We have a poor people problem.
In much of the city land is close to free. This isn't SF or NYC or DC where absurd land prices have boosted housing/rental prices. Lack of affordable housing just isn't the problem. Lack of money is.