Yes, we have been exposed to this in at least two other novels. wharton may be trying to portray the ultimate silliness of the upperclass to covet wealth above anything else. I need to go back and read about her upbringing and see if there is a connection.
this book on 'manners' may be to show how one can place themselves in society with the right kind of training and intuitiveness as Lilly did when young, ( or how she was taken in by her Aunt, because it was the mannerly thing to do, who gave her a small allowance, because it was expected that she should) and how another person can just as easily extricate another person fromthe upper crust if it is handled in an aristocratic (and mannerly) way.