Perhpas this is similar to Anne Elliot consoling herself for having a more elevated mind when compared with the Musgrove girls. However, the difference between Anne and Elinor, and Marianne is that Marianne does not value the Middletons or Mrs. Jennings in any way, while Anne and Elinor strive to treat everyone with respect. It is typical teenage behavior, IMO, to completely dismiss people who are in any way different from one's self.

Here's an example when E and M meet with Edward on his way to visit them:
"Have you an agreeable neighbourhood here? Are the Middletons pleasant people?"

"No, not at all," answered Marianne, "we could not be more unfortunately situated."

"Marianne," cried her sister, "how can you say so? How can you be so unjust? They are a very respectable family, Mr. Ferrars, and towards us have behaved in the friendliest manner. Have you forgot, Marianne, how many pleasant days we have owed to them?"