Why did you read this confusion into my post? Was it because I'm using YouTube thumbnails as an example or referring to A/B tests that websites employ to measure engagement?
These were concrete examples used to describe abstract concepts relating to human behaviour. The quality of a design affects how a user engages with the product, how they feel about the product and how they enjoy using it. I never really considered "marketing" in my comment at all. I was talking about demonstrable design elements (composition, mise en scene, copy, typography) and how those elements combine to affect the quality of the finished product .. and how that quality impacts user experience. This applies whether the "product" is ad copy or a physical object bought from the store.
It's also a good example: you can have an excellent video, but if the thumbnail (marketing) is not spectacular enough, people won't watch it. Another example about how people care little for quality.
This is completely orthogonal to whether the marketing campaign for said laptop is well made and hits certain conscious or unconscious buttons to make you want the laptop.
Now, I don't agree with the author, but the reasons are completely different. I would say that differences in design that end users don't notice are not relevant. Any design school that holds that one design is better and another is worse where the end users of those products wouldn't notice the difference is, by definition, a form of snobbery and a bad school of design.