Indeed I should not have made assumptions about your readings even if your familiarity was not apparent in your post. What I mean by strawman arguments is present in your response as well. You should not assume that people equate plastic to inferiority; more likely they equate bendy, twisting, creaking cases, dust-collecting seams and an unappealing tactile sensation with low quality, and in most cases this is a good gauge even if the product has fast components, great battery life and impact resistance. On a statistical basis, excellent designs have good to great components and few of the listed problems. The reason is the difference in the design process. Apple designers or the IBM Thinkpad designers understood this and for them, putting together a product was different from hardware architecture + assembly. There are some interesting readings of what went into Thinkpad desings and how they formulated their design language.
In your response referring to ZAMM, there is a strawman again, as the serviceability (and impact resistance, type of material etc.) of a product is mostly orthogonal to the question of subjectively experienced quality. For example, my R.A.T. mouse is attractive to look, hold and use; its exterior is mostly matte plastic that's not brittle and not flimsy, being ergonomic just the right way. It is also a most serviceable mouse, with accessible screws and a wide range of adjustment options. Impact resistance is good. A lot of thought went into it and the use is flawless, the feel is premium.
So let's not assume that someone who is knocking a product as plasticky or having a cheap feel can be reduced to the obvious observation that a product that contains plastic actually contains plastic. It would be childish. If it feels cheap or plasticky, then it's something some of us will possibly avoid. Bringing in aspects of design does not imply that your discussion partner misunderstood ZAMM, it might have been your way of returning some hostility.