The billboard, for local baseball, declared:
AFFORDABLE, FAMILY, FUN.
Whoa! I may've been speeding on the intrastate as I spied the sign, but I nevertheless feel my recollection is accurate.
Why those commas, copywriter dude or dudette?
I recognize that some folks believe punctuation is wedded to sound. It is. To a point. Punctuation choices (e.g., employing or not employing commas) certainly can be influenced by desires related to cadence and rhythm. Subjective considerations along those lines might turn out to be important, especially in poetry or in a speech.
Punctuation also conforms to rules of structure and logic. In the example above, logic is defied as to why commas are employed. In fact, the commas nearly make me laugh.
Granted, one could argue that copywriters readily use periods for dramatic effect, to slow the reader down. As in: AFFORDABLE. FAMILY. FUN. That might be mighty fine except in this case the lack of parallelism is jarring. We have different parts of speech. It throws the train off the tracks.
And no commas matter, too.