What the rules of grammar say?
If the "rules of grammar" do not reflect how language is used then it is the rules that are wrong.
Grammar attempts to describe the consensus for how a language is spoken. English grammar is rather ambiguous, due to the mixed heritage. The language developed from competing occupations, before being exported around the globe. Despite the ancient roots English remains one of the fastest evolving languages, as far as I know.
Punctuation, on the other hand, is just a series of marks intended to make the written word easier to understand.
Open punctuation whereby the reader is left to infer their own punctuation reduces English (a remarkably flexible and expressive language) to the lowest common denominator.
Imagine speaking the following words to the mechanical beat of a metronome.
And now the end is near and so I face the final curtain my friend I will say it clear I will state my case of which I am certain I have lived a life that is full I have traveled each and every highway and more much more than this I did it my way.
In fact I doubt that there are many native and adult English speakers who could say or read those words without subconsciously adding punctuation to them.
The more this Thread continues the more convinced I become of the validity of my second point in Reply #4.
Punctuation is vital, to convey the cadence of English speech and thought. Meaning does not depend merely on the arrangement of words but also the formation of phrases. I hope the lyrics I quoted above demonstrate just how powerful punctuation can be.