The quote in that linked article, "As new housing ages, it depreciates, and prices and rents decline, relative to newer houses" links to another article they wrote[1]. That article just shows a graph showing rental price vs age of a home. Its already established now housing is typically built for mid/upper class--where else would everyone else go? It doesn't show that lower class housing is being properly addressed, it's just using circular logic to prove itself right.

[1] http://cityobservatory.org/what-filtering-can-and-cant-do/