How many people in Appalachia can afford a down payment on any house? From a quick search of the addresses you linked, all are in places with high rates of property & violent crime. None of them seem like better options than being poor in your home town, and avoiding the myriad risks associated with big moves when you're a low earner who can't take any hits at all to monthly income without major sacrifices.
Neither Troy Hill nor Duquesne Heights nor the South Side Slopes nor the entire city of Morgantown are terribly crime-ridden, by either personal experience or any statistics that I know of. Troy Hill is the 'worst' area but mostly has low-level quality of life crime. High crime neighborhoods generally have $30k houses, which are too cheap to mortgage and bought by investors that rent them out until they're falling apart, then abandon them.
Both Pittsburgh and Morgantown are pretty prosperous, yet remain affordable enough for blue-collar workers to own homes close enough to the center of the city to commute by foot, bus, streetcar, funicular, PRT pod, or bike. The neighborhoods I posted are a bit rundown, but perfectly livable— I'd live in any of them.
The schools aren't necessarily great in the Pittsburgh neighborhoods but they usually aren't in rural Appalachia either.
I don't disagree that moving is hard when one is poor and one relies on one's social connections for a lot of support. It's just not because of a lack of houses in the prosperous parts of Appalachia.
Housing shortages on the coasts are a huge issue, and a huge issue for national inequality— but overbuilding and inner-city abandonment remain a bigger issue in a lot of cities in the middle of the country.