I was thinking of reader “prejudice” from a slightly different angle. If we “met” Edward ourselves and then heard Elinor and Marianne's opinions of him we might be inclined to agree with one or the other and focus on whether they are right or wrong about Edward. As it is since we don’t know anything about him ourselves it keeps our focus on the differences between Elinor and Marianne, as Elbč describes, without forming prejudices toward either based on these opinions.