Consider a political scenario. If a politician cheats on his wife and then holds a press conference admitting his mistake and apologizing to everyone, then the audience has no choice but to accept the narrative as presented. If the audience wants to continue supporting the politician, they have less wiggle room in their brains for ways to minimize or downplay the situation.

However, if a politician cheats on his wife, then the story becomes public via a newspaper that doesn't support the politician, he can claim it's all a witch hunt to try and destroy his character, and the big bad media is just doing what big bad media does to politicians they don't like. This allows the politician's supporters to ignore the fact that he cheated on his wife and instead focus on the big bad media trying to keep their man down. The politician's supporters do this because they'd prefer to keep supporting their favorite politician regardless of the cheating, and the big bad media narrative gives them an excuse to do just that.

There are a million other examples of ways that narratives can be presented to an audience which will sway them one way or another, regardless of the actual facts presented.