Sorry to be pedantic, but your very first reference confirms what I said:
>However, sometimes the situation isn’t so cut and dried. There’s a set of adjectives (including perfect, infinite, and unique) which fall into both categories, gradable and absolute. (...)
>(...) unique has developed a weaker, less precise meaning: ‘very remarkable, special, or unusual’. The historical Oxford English Dictionary first records this sense in the 19th century, and it’s now well established. The ‘very remarkable or special’ meaning is not an absolute concept and is therefore gradable, so it’s grammatically acceptable to use modifying adverbs:
√ I saw a guy wearing some really unique eyeglasses.
√ They’ve devised a highly unique way to cook and serve meals.
>However, sometimes the situation isn’t so cut and dried. There’s a set of adjectives (including perfect, infinite, and unique) which fall into both categories, gradable and absolute. (...)
>(...) unique has developed a weaker, less precise meaning: ‘very remarkable, special, or unusual’. The historical Oxford English Dictionary first records this sense in the 19th century, and it’s now well established. The ‘very remarkable or special’ meaning is not an absolute concept and is therefore gradable, so it’s grammatically acceptable to use modifying adverbs:
√ I saw a guy wearing some really unique eyeglasses. √ They’ve devised a highly unique way to cook and serve meals.
http://blog.oxforddictionaries.com/2012/05/an-extremely-most...