People are sometimes careless when they write and when they read but a comma does indicate a short pause. So yes, strictly speaking, the “decision to pause” (which is not really a decision) is determined by the presence of a comma.
Often the presence of a pause changes the meaning of the list; there are several examples in this thread. In these cases, adding or removing a comma does alter the meaning of the sentence and should be avoided.
Without Oxford comma: "We invited the strippers, JFK and Stalin."[two named items in the list]
Reading with or without the pause is natural either way. And massively changes the meaning of the sentence.
I think that your analysis in [] is wrong. Your second example says two named items but it still has three - strippers, JFK and Stalin.
This specific example is nonsensical to demonstrate the possible confusion, but this sort of confusion is really common.
> I think that your analysis in [] is wrong. Your second example says two named items but it still has three - strippers, JFK and Stalin.
No, in the second example, JFK and Stalin are two instances of strippers. So there are three nouns, but only two people.
In the sentence without, there are two strippers, the first named JFK, the second named Stalin.
Here’s a drawing to help… http://helveticka.com/blog/wp-content/uploads/2014/08/oxford...
With Oxford comma: "We invited JFK, the stripper, and Stalin."[two named items in the list with an appositive affirming that we're talking about JFK the stripper and not the former president]