Your theme song for this post:
Who gives a fuck about an Oxford comma? Not Vampire Weekend and not the University of Oxford.
Galleycat has reprinted a bit of their style guide:
As a general rule, do not use the serial/Oxford comma: so write ‘a, b and c’ not ‘a, b, and c’. But when a comma would assist in the meaning of the sentence or helps to resolve ambiguity, it can be used – especially where one of the items in the list is already joined by ‘and’ [for example]: They had a choice between croissants, bacon and eggs, and muesli.
What? How? Why? Who thought that was a useful piece of advice?
Later, a reader clarified that that was from the style guide for the PR department, not the university itself, but whatever! Let's not allow petty facts to interrupt this opportunity for sputtering indignation! This is the internet, after all, which (as Paul Constant has wisely pointed out) is fueled by outrage!
Why would any style guide leave ambiguity about when punctuation "would assist in the meaning"? That's crazy. All punctuation should be designed for clarity—for helping us idiots better express ourselves. Leaving discretion ("when a comma would assist in the meaning") is the opposite of what style guides are for.
Like a saline bag for a patient admitted into the hospital—maybe the patient is plenty hydrated and doesn't need it, but it can't hurt. Isn't it best to err on the side of caution in case your patient (or your sentence) does need it? Just make the help part of the protocol. That way, you will avoid unfortunate cases of neglect-induced dehydration and sentences such as these:
... highlights of his global tour include encounters with Nelson Mandela, an 800-year-old demigod and a dildo collector.
... we invited the strippers, JFK and Stalin.
It's a small thing, but an important and useful thing. Like a vegetable peeler. Any kitchen doesn't necessarily need one, but it's cheap and low-maintenance and makes life easier.
And I've about exhausted myself with overwrought metaphors on this subject. What do you say?