They matter because they tell us things. They matter since, disregarding the mental sewers, the dark cringe corners of mean wishes and strange ideas next to blue prairies; they tell us who we are. Like letters or half sincere posting in Facebook we laugh of due they’re full of meaning.
Did you get anything from all this defining?! Not even older (as in experienced) writers can define it. But it seems so worthy, it seems there can’t be plot without scenes.