I'm not denying commas are important. As Truss says in her book Eats, Shoots & Leaves, a humble comma can change the sense of a sentence. Take for example:
"Verily, I say unto thee, this day thou shalt be with me in Paradise" and compare it to "Verily I say unto thee this day, Thou shalt be with me in Paradise." See how the meaning changes?
The Oxford comma is the one that comes after white in the sentence "The boat is red, white, and blue." In the UK, the standard usage is to omit it. In America, standard usage is to put it in.
Since the comma is one of those markers in language that indicates where the reader
What I do find confusing is when to use commas joining two complete sentences. When I'm edited in the US, they take out the ones I use, and put in ones I wouldn't, and I can't always see why. In the UK, commas are used with conjunctions such as and, or, but, while and yet. But we never do it with however and nevertheless.
Just to make life even more confusing, there's something called the splice comma. When the conjunction is omitted and the comma is retained, when it should really be a semi-colon - that's a splice comma. Example: Pansy woke up in an unfamiliar bed, she felt odd. Famous writers like Updike, Beckett, E.M.Forster and Somerset Maugham use it, and get away with it. Used by them, it is considered dashing, poetic and effective, says Truss. Done by those who don't understand the rule, it is awful.
All I can add is that I get very confused when the grammar I learned at school and have used all my life is deemed to be incorrect. I sit here and muse how very different the novels of Nora Roberts would be if her books were put into UK English before they were loosed on the British public. Watch caps and Oreoes? What the hell are they?