I never said plastic should be used for clothing, though I am not saying it should not be used. I justt have not studied enough about it. My naive guess is that in general clothing made out of “only” plastic may not be comfortable due to other reasons (surface finish, general stiffness and flexiblity, permeability and what not). And Micro plastics is not a problem unique to plastic (well maybe micro “plastic” is unique to plastic if we are being pedantic), basically all materials undergo abberation, and resultant micro tears or fractures result in micro debris for all products - ceramics, metals (less for metals due to some other reasons, what you usually get corrosion products) and plastics. And in general all these micro “things” are harmful to us, some more some less (due to the fact that we are not isolated, we have intakes (breathing, feeding, drinking, and general absorption, and then eventual accumulation - which may result in damages, for example, absestos, is basically micro silica, binds alveoli). In fact (not very rigorus statement, more of a statement on whole classes instead of extreme cases) among these micro “things” - micro plastics would likely be least harmful because of “almost” inert nature of plastics

Though I completely agree with your narrow part (contained is not necessary due to above stated reasons, basically it is unavoidable). And I also agree with your part of alternatives that don’t last forever, and clothing, or packaging in general is indeed the best use case for this