I am like most who have answered on this--I use plastic storage bins for much of my fabric. I am not convinced that the theory of not using plastic is a fact, as opposed to what somebody just wondered about. Seems ideas can sometimes become facts rather easily and without any factual data behind "the fact". I wonder if this idea might have arisen when plastic containers were new and at that point the "old way" seemed better???? Also I think I remember the early plastics having a lot more chemical smell to them than the ones we get now do, which might have lent credence to the do not use plastic idea?
Maybe one of you is a chemist and can give us a really definitive answer.