No I don't think I agree that it is like alcoholism, not really - except that it is probably just as difficult to accept that you are a hoarder and need to stop!
I think it's more of a safeguarding thing, as someone up thread has said, and can be triggered by a traumatic loss of something. My Mum was something of a hoarder (not terrible, not like those mentioned on here) because when she was 7, her mother disposed of all her toys bar 3 teddies. Because of this, Mum never got rid of any of our toys, unless they were actually beyond repair.
Dad is the same - because his collection of comics were disposed of by his mother (things like the Dandy from day 1! it would have been a very valuable collection). Dad still collects - stamps and coins - all of which have an inherent value but he won't dispose of them because they're "his collection". It will be down to us to dispose of them when he's gone (not any time soon, I hope!) but of course he'd rather we didn't. We will - none of us "collect" - but it will be easier for us because we don't have the sentimental attachment to them.
I also agree that some of it may come from the "make do and mend" attitudes post-war - both my parents were alive during WW2, although Mum was only born in the latter years, but they both grew up with rationing - so keeping random bits of stuff that might come in handy was a standard thing. I still do it - but not to the point of having boxes of it all over the place.
I've heard some people say "if you haven't used it in a year, you're not going to so get rid of it" and I always scoff at that because I have many things that I won't necessarily use year to year, but when I do need them, I don't want to have to go and buy them again! Fish kettle is one; mitre saw another.
I had a collection of egg boxes in my cupboard, for craft purposes, at home or at playgroup. Someone wanted some eggboxes for actual eggs (she has her own chickens and too many eggs) so I said I had some she could have - only I didn't! They'd been cleared out.
OK - that's my self-justification over. If my "hoarding"had the same impact on my family as Fideliney's DH's does on hers, or anything like as bad, I would hopefully do something about it. But it doesn't. (Honestly!) I actively dislike minimalism and show house styling - it looks so unhomely.