Yes, it is often true. Conflict drives the story forward. It creates tension and keeps the reader engaged. For example, in a mystery story, the more conflicts between the detective and the suspect, or among different suspects, the more exciting the story becomes.
Well, generally speaking, it's true. Conflict can be of various types like character vs. character, character vs. society, or character vs. self. The more of these in a story, the more complex and interesting it gets. Take 'Romeo and Juliet' for instance. The conflict between the two families adds so much depth to the story. Without it, the story would be just a simple love story. But with the family feud as a major conflict, it becomes a tragic and powerful tale.