Why is Lady Bracknell so strict with who Gwendolen marries?

Lady Bracknell is all about social class. She seems straight out of a Jane Austin Novel. Social mobility is meant to go up and not down. The quickest way to go up is to marry better. Lady Bracknell is adamant that Gwendolen should not stoop so low as to marry someone like Jack. She recalls her own experience as something for Gwendolen to strive for,

"When I married Lord Bracknell I had no fortune of any kind. But I never dreamed for a moment of allowing that to stand in my way."