What would happen to writing if paragraphs didn't exist is that when the reader reads the writing, he/she might skip a sentence or even get confused. And then you might not understand it yourself. It can affect the reader by not understanding what is going on in the writing if it's a story.
Yes. Some of them doesn't exist in real life but still look like it does exist on earth.
communicate effectively with the intended audience
Of course I don't know a list to pick from but I would say pride, dignity, etc.
