But you need them, sometimes.
In chiaroscuro, the darkness about the central light focuses attention on it. In a story, removing distracting drama focuses on the main plot.
This is why you have the Good King who can clear up the problem if only you manage the dramatic escape to reach him. This is why so many main characters have no siblings and have a (1) parent living if and only if the parent-child conflict is central to the story. (Parental support of the child, or vice versa, is of course rare because you need a problem that can take both of them to fix and even there it's a difficulty.)
So, working out the details on when the hero's mother died so the hero and his father can be the only characters in the story. . . .