Perhaps the most aesthetically displeasing problem with an Oxford comma-less sentence is a list containing merely three words. “Bananas, apples and oranges” appears inherently incorrect because the words clearly aren’t receiving equal attention. However, you might never have considered that there could be a problem of practicality to this inferior structure as well.
Transition! As with all fine writers, I prefer to follow adverbs and adverbial phrases with a comma when they come at the beginning of a sentence. “Excitedly, Jeff goes to the store,” in my opinion, looks and sounds better than, “Excitedly Jeff goes to the store.” Considering how diverse and complex adverbial phrases can become, the lack of this comma can result in some immediate confusion.
For example, let’s say that the previous sentence didn’t have that comma: “Considering how diverse and complex adverbial phrases can become the lack of this comma can result in some immediate confusion.” A reader’s mind that is of sound linguistic logic would initially read it as though “diverse and complex adverbial phrases” might become “the lack of this comma,” which doesn’t make sense in any regard. Ignoring this due comma can have even more disastrous consequences when things are even more complex, when adjectives and nouns and such get in each other’s business without some punctuation to keep them in their respective private zones.
In fact, problems can arise in simpler instances as well. Going back to the first example, what if the introductory word were one of those reproachful ones that serve as both adjectives and adverbs? “Fast Jeff goes to the store.” “Fast, Jeff goes to the store.”
Now that I’ve justified this incidental stylistic superiority, consider what dreadful consequences might come about if a three-word grammatical list (without the Oxford comma) were to combine with an adverbial phrase at the beginning of a sentence:
“In the midst of chaos, terror and despair were beacons of hope.”
Huh? Chaos and despair certainly don’t sound like beacons of hope. Let’s fix this.
“In the midst of chaos, terror, and despair were beacons of hope.”
Ahh. There were beacons of hope within all this terror, chaos, and despair, I see.
Then again, terror and despair might be useful if you’re an autocratic ruler whose country is falling into chaos.