Native English speakers(L1 ones) are the best in articulating all aspects of it,fact or opinion?

Ahmed and Mohammad are both correct in principle but there is a saying which goes "Familiarity breeds contempt", used in this context it implies that Native English Speakers can become "lazy" with their own language as they are so used to it! Also they use Adverbs, nouns, adjectives and all other facets of the language on a daily basis but many of them couldn't actually give you a definition of what each of them was, unlike those people who are learning the language.

it is a fact .They listen to the language from the main source.Their parents , families and society.

I believe it's a fact, since all native speakers receive lifetime practical training in that.