If you own skis (or any of the other items), you don't just own some skis; you own those skis. They're sized to you, you've used them the last 100 times you went down a mountain, you're accustomed to exactly how they handle, and the left ski boot's padding is a little more spacious because your left foot is a little bigger, and has worn away the padding more.

Yes, you don't use them, but between the custom fitting and the emotional attachment, they aren't fungible anymore. Which is, I suppose, the point of the article: if you declare something to be freely exchangeable, then you can have a much more freewheeling style of life.