I eventually realised he bought things without thinking about where to put them, when he got home with it. So it just sort of would get abandoned wherever. There was no assigned "away" for him, and I was assuming there was. Baffling, but at least it wasn't passive-aggressive like I had thought. Some of my habits eventually wore off on him, thankfully.
A related theme is: I don't have anywhere to put this even after thinking about it -- then you probably have too much stuff!