Why does a passage have an implied main idea but not an implied central point?

A passage can have an implied main idea because it conveys a general theme or message that is suggested rather than explicitly stated, allowing readers to infer the underlying meaning through context and details. In contrast, an implied central point would suggest a specific argument or assertion that the author intends to support or prove, which may not be present in the passage. Thus, while the overall theme can be discerned, it might not lead to a definitive conclusion or argument, resulting in an implied main idea without a clear central point.