* skills gap ( handling ideation, flows, projects, organizing possessions )
* resource starvation ( cf Traps, Supertrap )
* coercive environment ( "nagging and yelling", prevalent in the books ) - at least, in a meaningful subset of cases under consideration ?
* Runaway Mental Processes ( RMPs )
* otherwise rational, internally consistent logic, with the original causes of a different nature
* other factors medical or non-medical, without loss of generality
This checks out by considering almost all examples provided in foundational books - e.g. Stuff. - plausible alternative explanations abound.
Ref also the fact that the primary triad of traits claimed ( emotional attachment to things, difficulty discarding "regardless of actual value" (sic), difficulty making decisions ) was not definitively demonstrated in these books ( to be demonstrated specifically ).
Authors / experts have yet to provide one geniune example of emotional attachment to things in general, representative of the bulk of person's possessions.
Everything seen so far indicates the contrary.