I had to read the Twitter thing four or five times until I, aided by the "Oxford comma" heading, realized where the assumed problem was. In Swedish, that comma is absent, if not even directly discouraged. So, I automatically, I suppose (I'm absolutely no psycholinguist), parse any enumeration to make sense out of it.
When translating from English, I can often resolve ambiguous lists by juggling the order of items, or for the ", and" use a synonym for "and", which fortunately is available to us.
I think English needs another form of printed "and", to handle complicated cases where you have "and" used to link items in a main list where the items are sometimes themselves lists e.g.
"the balloons were coloured green and blue and yellow". I'm trying to convey that the balloons were either green or blue and yellow. I'd like to propose the use of & as a standard to link subitem lists e.g. "the balloons were coloured green and blue & yellow".
This would also work in the above case.
I know this is wishful thinking but it would spare some confusion.
(BTW the example is not the best )
This is not an argument for the Oxford comma, merely another example of a case where using the Oxford comma would make sense. If anything it's an argument for not blindly following some rule (AP vs. CMoS) stipulating that you must or must not use the Oxford comma. Lugubert's comment makes the most sense.
I'm not sure I agree Faldone. Why does reordering a list make more sense than simply using 1 character? It seems more effort to reorganize thoughts so that they can be expressed without need of an oxford comma. Why put forth extra effort to save one character? I jokingly tell people that we must be running out of commas for people to put forth such effort to remove 1 keystroke.
I believe there is a conventional meaning to the distinction between 'and' and '&' in Hollywood movie credits – one will frequently see something like "Screenplay by John Jones & Mary Miller and Sam Smith" meant to indicate something or other which I don't know.
I believe I use such a distinction in spoken English: if the balloons were red and green-and-blue (which is how I would write it) I'd pronounce the first "and" something like "und" and the second "-and-" something like "n", and much more run together with the adjacent words.
It doesn't work at all with the sentence at the head of this post, though; only with compounds like "green-and-blue".