No? I'm an exceptionally good writer - especially essays and the like - and I have friends who will, no matter how much they practice, never be as good as me. My friend Craig, for example, grasps certain philosophical concepts easier than me (if I don't get something straight off I throw a strop with it) and works a lot harder than me yet he does worse than me in exams simply because he can't write that well, whereas I can bullshit my way through a lot of it.
I was reading simple shit by the age of two; I was onto roald dahl by three and I was reading thomas hardy and george eliot by five. Reading, writing, spelling and comprehension have always come naturally to me. To say it can just be learned is simplistic at best.
Basic Writing, like basic sports talent, is a skill. If you train, know the rules of the game, and are taught the basic strategies you can pick up almost any game.
Great Writing, like truly exceptional sports talent, is a gift.
Reading and writing have always been my strong suit, but I used an elective for a written communication class and it helped me refine it. Basic proficiency in nearly any area can be taught and learned, but to excel to something spectacular it takes either great genius or great willpower. Even though I was the political antipode of my Written Communications instructor (one of the reasons I took the class, actually), his most important lesson was conferred on day one: Writing is a skill.