Of course it's a skill. Yeah, anyone can write. I mean, you get the fine folk who are sick of working their jobs and say, "I can't wait to retire, settle down on a beach somewhere, maybe write a book." I laugh at those fine folk, and I await the day.
I mean, sure anyone can write...anyone can hit a keyboard. Somewhere, there's an infinite number of chimpanzees writing Shakespear. It would take those chimpanzees an even longer amount of time to write an original work of fiction which would move you, the audience, and stir you to emotion. That's where writing skill comes in. You learn your basic tools, your grammar and your sentences, your spelling...but what makes it a skill is learning to write a story that makes people
feel. It doesn't matter if you stir horror, guilt, love, happiness...you're making them feel something using the same words that another person could use to write a grocery list, or a credit card offer. That's a skill.
What I've always found personally amusing (in a bitter* sort of way) is that no one denies that a magician on a stage is practicing his
trade, making use of his
skill, to do his
job...but if you're an artist or a writer, you're just a hippy-beetnic college kid who's dancing around getting a real job.
Crazy ol' world, eh?
* I'm not actually bitter. Honest.