My parents (born in the late 30s-late 40s) just moved from a 5 bedroom house larger than my own into a 2 bedroom retirement apartment.
The house sold more quickly than expected, so they were in a panic to move out.
They're not hoarders -- in fact, the house was always impeccably tidy, and not at all cluttered.
They had to get rid of SO much stuff. My dad was an only child, so he had kept so much stuff from his father before him. My mom was one of many, but the eldest, and the family archivist, so she has the photos and old movies and stuff.
Ultimately the biggest problem is their children (my sister and I) DON'T NEED THEIR STUFF. We're adults in our 40s and 50s. We have houses of our own, filled with furniture of our own. Smaller houses than our parents', smaller garages, already more cluttered than our parents'.
Yes, we took on some keepsakes we love, we took on some furniture to upgrade our own. But mostly, there just isn't room. I don't have room for 2 generations' worth of accumulated tools, no matter how handy they may be. I don't have a house full of empty walls waiting for artwork and pictures. We're already storing heirloom china from my wife's side of the family that we haven't touched in the 10 years we've had it, we don't need to store another set of heirloom dishes we'll never use at dinner parties we'll never hold.
As generations get spaced further and further apart, the heirs no longer need stuff to start lives of their own. As property gets more expensive, our homes get smaller, so we wouldn't even be able to use all the stuff if our homes were empty!
As a data point, I counted all of the chairs at my parents' house. 44. 44 chairs. We thought it was hilarious, so we told my in-laws, and they counted chairs at their own home -- also 44!
Oh, man. It's getting to that time where I can see downsizing my parents' stuff as being on the horizon.
There's so much of it that is unremarkable. It fits into their house+garage, but it consumes a great abundance of space. There are, IIRC, 3 generations of China, each with its own China cabinet -- and I wouldn't know which dead person they once belonged to anyway. Tools. Furniture. Stacks of rough-sawn hardwood lumber, and logs.
I have enough furniture. I don't need rolling toolboxes full of mixed hoarded socketry, unsorted wrenches, and rusty tap-and-die sets in inch-standard sizes. The bench-mounted belt sander my dad made from scrap 40 years ago is cool and all, but it's been over 25 years since he's bothered to have it set up, it was always finicky to get running true, I've never suffered for a lack of using it.
If I ever move stuff like the tools and the lumber, I want it to be the very last time it ever happens -- and then I never want to see it again.
The China is particularly daunting: For as long as that stuff has been sitting around on display at their house, it has been both too nice to ever use and also too good to get rid of. (If the time ever comes that I want my own set of nice China for whatever reason I might, then: It's easy to get.)
I will work hard to dissuade anyone else from taking anything that is physically big, just on the basis that nobody needs that kind of curse in their life.
But I fear that others will find that a lot of this stuff will be too emotionally-precious to depart with. It will then be "temporarily" relegated to a storage facility until enough years go by that someone finally gets sick of paying the bill and it all gets sold to the highest bidder, thrown away, or donated anyway.
That expensive trip through purgatory seems like such a waste of money and effort.