Can’t guarantee quality when you have a billion hardware permutations.

What about vendors like Asus, Dell, HP, Lenovo? Don't they have any QC?

Going by the article, Asus clearly don't. Given the stories floating around about the others, I doubt they have it too, except maybe Lenovo on Thinkpads and the like, although they too aren't immune from problems that really should be caught in QC.

Which vendor has a billion hardware permutations ?