Back on topic. I have never understood this argument: He refuses to throw it out, thinking someone will find it useful. Those who hang onto useless stuff often use this line, and it makes no sense. If someone will find it useful, I'd want to shout, then let it go out there so that "someone" can find it. They can't find it in your basement.
This is why I rarely will agree to help anyone clean up. Unless they are truly motivated and willing to take action (and not justify the keeping of every piece of paper or other thing) it is a hopeless and frustrating activity for both parties. One can help but one cannot motivate.
Honestly, I don't think it's rational, and that's why rational arguments don't work. This is my experience with the hoarders in my family, anyway. My dad has a lot of old computer stuff around and I thought about mentioning the Best Buy recycling thing to him. I'd say there's a 75% chance it would change nothing. Because he's not really
keeping them for someone else who needs them, or because he doesn't know how to get rid of them safely, or because someday he's going to fix them up--those are just words he says when my mom asks him to get rid of the stuff, to make her stop asking. Hoarding is, from what I've seen personally, a deep-seated irrational fear of getting rid of things, even absolute junk in bad condition--it almost seems to cause physical pain when you suggest or try to make a hoarder throw something away.
Now, not everyone who keeps stuff is a hoarder, of course. I think sometimes otherwise normal people get fixated on one THING, even if they're perfectly willing to throw away other stuff--I still think it becomes more about what the thing represents, than about the thing itself, though. Like, "If I throw this out, it means I'm admitting I will never actually learn to speak Chinese/water ski/quilt--it means I'm giving up on that dream." What can I say, growing up with many hoarders around me, I feel like cleaning/decluttering is so much more about psychology than physically moving stuff.