I like that take on on the meaning of the term because it fits in so well with the whole theme of upward mobility in "Emma", and especially the anxiety that causes in the titular heroine. Examples: as already pointed out, the Coles; the question of who is a suitable suitor for Harriet; Emma's being seemingly unaware that some might consider Mrs Weston's marriage an unequal one, but taking offense at insinuations about it.