My two Spanish teachers, who live in two different Latin American countries, use the RAE as a fallback authority in cases where it’s not clear what usage is preferred. So it is kind of a weak authority. And, believe it or not, the concept of correctness in language exists in Latin America, regardless of what the “locals” speak, and it matters to a lot of people, who love their language and treat it with respect.
My Spanish teachers from Argentina did the same. When coming across words and phrases that they were unfamiliar with (hey, they don't have the dictionary memorized either) they almost always sent me something later (or brought it up in the next session) citing RAE or a source that itself cited RAE.
Also, the best online dictionary for Spanish is the excellent one at the RAE site (although it only works once you know enough Spanish to read the definitions!).
Sure, the Spanish teachers do. The Americans? I still doubt it.
Well, but the baker and the policeman in Paris are not preoccupied with conforming their speech to the dictates of the French Academy, either. But it is still recognized as a kind of authority for many purposes, although, I’m sure, often begrudgingly.
By Americans he means the locals. The (Latin) Americans.
I read his post as explicitly saying that he was not meaning that.