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.