One of my favorite things about AP style is that it doesn't employ the Oxford comma. At least in most circumstances; sometimes the O-com has its uses, such as when a list has an "and" within it. OK.
But the clarity purpose only goes so far. Advocates of the Oxford comma constantly spout sentences such as "Her children, Odin and Barack Obama all got stuck in the storm" as proof that we need the punctuation mark. Wouldn't want anyone to think the subject is raising a Norse god and the president! Nyuk nyuk!
That's the thing about most of these examples — they're misunderstood only in humor. Even with no punctuation, it's clear that the children, Odin and Obama are all different people. If that isn't clear, then the person is either joking or they have a comprehension problem that an extra comma isn't sufficient to solve.
Even more importantly, they're badly written sentences. If they crossed my copy desk, I'd restructure every one of them to make them clearer. And I'd do it without needing the Oxford comma. Like I did with these examples.
It's important too in this debate to differentiate between styles of writing. Clark's example of a sentence needing the Oxford comma is an 89-word literary run-on, the structure of which he argues is necessary to convey the meandering of the river it describes. In other words, exactly the kind of discussion you'd have in a grad-school lit course. But no 89-word sentence is going in a newspaper except as several sentences. It will never need AP style scrutiny.
I've been through the English grad-school grinder and I've been active in journalism for the past 16 years. I once wrote an MLA-style term paper, a news article with AP style and a psychology paper (APA style) simultaneously. So I can tell you that journalism and literature (and, really most other forms of writing) are so far apart that they're almost impossible to compare.
Literature is wide-open in terms of style. Yes, it has its own style conventions, but ultimately it's a creative endeavor. You can write 20 pages about what a flower looks like. And you can Oxford-comma the hell out of it, because no one's asking you to be maximally concise. Sometimes, it reads better in a literary sense not to be tied to grammatical rules.
But journalism favors economy. It's written in a concise style intended to fit in a certain space, and copy is aimed at people with a common reading level who might not read past the headline. AP style addresses those particular needs, just as MLA, Chicago and other styles govern other forms. Not just punctuation-wise, but in how words are written to avoid reader confusion. AP is not arty, but it is an art in and of itself.
I don't think AP style should apply to literature, and would never insist it should. Literary people should extend the same courtesy to us. That mutual understanding would make this much less of a debate.