Several of the points in that PDF are also about conservation and protecting the forest and wildlife, which I was going to mention as well. Nearly all of the ski hills around me also maintain a fair amount of forest in a sort of conservation area, but also used for cross-country skiing. So you get a ski hill, x-country trails, and many many acres of fairly protected forest.

The resort also uses those trails (and hills in some places) in the summer for hiking/biking so they still have some revenue year-round.