Given that so much of today’s writing is done via text, punctuation might not seem important 2 u. But for the author, there’s a good reason (beyond convention) to adhere to an internally consistent set of rules. Punctuation is a clue, from the author to the reader, as to how the author’s sentences ought to sound. The author writes a verbal song, and it should be sung as the author envisions. If the author writes down the wrong notes and beats, there is no chance for the reader to enjoy the original vision.

For example, if a sentence reads aloud like two sentences, make it two sentences. Read this out loud: She was angry, her voice carried into the next room. The structure allows the appearance of a longer, more complex (read artistic) sentence, but read out loud, the passage will sound like two sentences. Why not make it so?

Commas place pauses. Parenthesis sets off an aside. Italics denote emphasis. A dash shows an interruption. Use these devices to make the sound of your word-song come alive.

James Joyce’s Ulysses didn’t need punctuation. But you and I are not James Joyce.

The following website helps me:
 http://www.grammarbook.com/
Start with the discussion of commas. No one, myself included, gets commas right.

Now, for a good counter-argument, visit another website for a list of great authors who ignored the advice I just gave you:
https://qwiklit.com/2014/03/05/top-10-authors-who-ignored-the-basic-rules-of-punctuation/