I just looked it up. I see what you mean.
There are lots of "shuttered" towns in Hokkaido, but the reasons vary @M_G. Yubari mostly suffered due to the low cost of, for example, Australian coal. It was a coal mining town and basically couldn't compete and went broke in the 80's and if you go up the valley from Mt Racey you'll see a lot of that disused infrastructure. Of course you have to add the aging rural population and the movement of youth to the cities to the big picture but in Yubari's case, its mostly about the loss of coal mining.The local town Yubari is famous as a microcosm of everything that was economically wrong with Japan in the lost decades. To see some actual investment going on now would be pleasing.
Locals did a really good job of reinventing the place though, with a well regarded international film festival, which still runs annually. In fact, with the local council on board, they even put up eye catching classic posters on some of the old buildings that were 2 to 3 stories high, the posters that is. It was (and possibly still is, I haven't had a look for a few years) an incredible site to see these huge 1950 American movie posters on aging buildings, against a back drop of rusting, towering mine equipment slowly being swallowed by deep grass and shrubs. Mt Racey is well worth a skiing visit. Gets the good cold Hokkaido snow so maybe some investment will help the resort and the town.