Writers hate rules. They'd much rather have pirate code, i.e. guidelines. Whatever you prefer, it's undeniable that having them is what makes SPaG (spelling, punctuation, and grammar) into understandable prose. In the same way that you need rules for your magic system or your handwavium or your worldbuilding so your story will make sense. The language that readers use to indicate that they had problems with viewpoint or point-of-view. Why writing is not the reverse of reading.