Randy Frost, in his book, Stuff: Compulsive Hoarding and the Meaning of Things, says we hoard stuff because we are prisoners of the stories the stuff tells us about who we are. He says you can get rid of the stuff in your life by recognizing and if necessary honouring the stories they tell.(This could explain why clutter doesn't seem to bother kids as much as adults. Kids are less perceptive. They build a coarser model of their surroundings, and this consumes less energy.)
I don't know exactly what he means by the second sentence - anyone? But I agree with the first sentence. When people are younger, they need stuff. With the stuff, they build their first home environment and help put together an identity. I think maybe we spend our first 50 years collecting stuff, and our next 50 years trying to get rid of it.