As far as I can tell, commas are inserted either to reduce ambiguity, or to indicate where a pause would be in spoken English (which are also frequently related to reducing ambiguity).
So the colloquial patterns of use are pretty deeply dependent on understanding the rest of English, so you can notice where it becomes ambiguous or starts to feel like they could almost be different sentences but the person who is communicating with you is ignoring that because their personal dialect doesn't have those pauses and you kinda just have to deal with that when it happens.
Every other rule-set I've heard has to be accompanied by so many exceptions, and has so many competing schools that disagree, that they're just dogma, not description. And they're extremely hard to remember. So they're more about socially signaling that you're part of the well-educated upper-crust than they are about communication.
And yes, I'm an Oxford Comma user. It reduces ambiguity.
Commas do follow rules, they are just hard to explicitly lay out. Usually they are used to separate clauses. For example, in some cases you need to use a semicolon instead of a comma to avoid the “comma splice” (though outside of formal writing this comes off as pretentious).
If you use commas only to denote when you’d pause when speaking, your writing can come off as juvenile or uneducated. It’s not just a signaling thing. It is jarring to read a sentence with them misplaced.
So the colloquial patterns of use are pretty deeply dependent on understanding the rest of English, so you can notice where it becomes ambiguous or starts to feel like they could almost be different sentences but the person who is communicating with you is ignoring that because their personal dialect doesn't have those pauses and you kinda just have to deal with that when it happens.
Every other rule-set I've heard has to be accompanied by so many exceptions, and has so many competing schools that disagree, that they're just dogma, not description. And they're extremely hard to remember. So they're more about socially signaling that you're part of the well-educated upper-crust than they are about communication.
And yes, I'm an Oxford Comma user. It reduces ambiguity.