I am sure there are different experiences out there, could also be the circle of friends that do a lot of IKEA "freecycling" meaning I do see a higher quantity of re-used items being moved about.
I know that depending on the type of item as well there is a build quality issue - like Kallax shelving, it is a little more sturdier than the slightly cheaper version, and given I started with Kallax, I have stuck with it - Same with the Billy book cases too!
Although, the Diam Cake you can get from IKEA... that 100% is not going to waste, and 100% no one is getting a "second hand" one from me... there will be none left ;)
But returning back! It could be Apples to Oranges, there are so many products, and in my experience I have seen people stick to the same grouping of products as well, which could see re-use more possible than say another grouping (for any number of reasons).
Who knows, tomorrow the shelf behind me might just fall apart and I will be back eating my own words :)
I'm very much surprised about the amount of comments here on HN (today and in many previous discussions) that claim to reuse IKEA furniture; it's completely contrary to my experience. My opinion of IKEA furniture is that it's single-assembly - trying to break it apart irreparably destroys it.
I conclude there must be either high variance in IKEA's production quality, or we're comparing apples to oranges. Maybe some IKEA products have more reassembly potential than others. Someone mentioned an office chair elsewhere in the thread - yeah, that obviously can last years and be moved, because it's made of metal and hard plastics. But most IKEA furniture I experienced is made of dried toilet paper glued with formaldehyde^W^W^W^W^W^Wmedium-density fibreboard and assembles destructively.