Death of a Salesman

Death of a Salesman Quote and Question

In the scene where Linda and Willy begin talking about finances and how much Willy actually brings home in a week, it becomes obvious that Willy fabricates his earnings for his boys' to hear. 

Linda says, "And the boys, Willy. Few men are idolized by their children the way you are."

Question: What benefit is it for the audience to see how the relationship used to be between Willy and his sons in contrast with their current relationship? How does knowing both time periods change the way the play is understood?