I like rules. There is a certain comfort in knowing where the lines are, in knowing the boundaries. Lawlessness makes me uncomfortable. True anarchy could never really happen. If our government ceased to exist--just one day poofed from existence--something would rise to take its place. People want to be told what to do, what's appropriate, and how they should act at any given moment. It's how dictators rise to power. People will follow anyone in a vacuum.
Liking rules isn't necessarily a bad thing. Because there's liking rules, knowing rules, following rules, and then there's breaking them.
Breaking rules is my favorite part of liking the rules.
King spends very little time on grammar. Enough time to say that you should know it. You should know the rules. I'm going to put it out there that I believe knowing grammar and KNOWING grammar are two different things. One of the reasons that I believe most high school and college foreign language courses fail students is that they teach you nothing about actually speaking the language. They teach you verb forms and mechanics and long lists of nouns, but very little about the actual language. Or more simply: you can't learn to drive a car from reading a book.
You can learn that verbs and nouns form sentences (Plums deify!) and that sentences form paragraphs. And so on. But that doesn't teach you the soul of grammar. It doesn't teach you how to write.
I realize as I've gotten to the end here that I seem to have put up two contradictory arguments. One is that rules are awesome, the other is that rules can't teach you to be a writer. But it actually all works (even if my coffee starved brain thinks otherwise). Here's the thing: I know what an adverb is. What an adjective and a gerund are, and how you shouldn't split infinitives or end a sentence in a preposition. I know those rules, which means I also know that sometimes, "He's got to have something worth fighting for. Something worth living for," sounds better than, "He's got to have something for which to fight. Something for which to live."
But I don't just know these rules, I feel them. When I'm writing a sentence, I'm not thinking about rules. I'm not thinking about verb forms. I'm just writing.
So know the rules, yes, but don't fetishize them. Break the rules, definitely, but not until you know them.
But above all: forget the rules. Just write.