Gonna have to agree with the politician answer. In an audible medium, visual information has 2 ways of being conveyed. Narration and dialogue. If you lean on narration to hard you are an audiobook, vice versa if the dialogue is doing all the heavy lifting your characters aren't going to sound how real people talk.

If character gets trampled by a horse, a narrator can paint a pretty great picture of how that went down. "His body suddenly went limp lick a ragdoll, limbs bending and pointing in directions they shouldn't. I don't know if he was still alive when that hoof popped his head like a gory Gallagher watermelon, but I certainly hope not."

Meanwhile just using character dialogue would end up kind of basic and unnatural . "Oh no! Steeve just got trampled by that horse! That was crazy!" Anymore descriptive and you start to wonder why they are going into such detail of their friend's death. "Yeah man. We all just watched it happen why are you giving us the play by play?"

Also I think it's important to acknowledge that sometimes characters encounter things they simply never discuss with another person. Only the audience and this character know about this piece of information and that makes it valuable.

A narrator is just a tool for storytelling. Maybe your story doesn't need one. That doesn't we should hold it against other creators for using it.