It has nothing to do with compassion, poor/rich, homeless, etc. A house is not a toaster or a car. You can’t move it from one place to another. If there are too many houses in one place (because people are leaving), then there are simply too many houses. Do you think homeless folks from San Diego would go to Detroit if they were offered free shelter there? I really doubt that. After all, some of those houses sold for $1 (the median price in the city of Detroit was $6,000 last month). I’m pretty sure even the homeless have $1 to spare.
It may seem frustrating for those of us leaving in crowded cities with housing shortages, but houses in some decaying cities like Detroit and Flint are as useful as houses at the North Pole.