Do Democrats also promote Candidates that will work against voter's interests?

No - what you are citing is like a trickle down economics theory. What I am saying is if the middle class is doing well, women, minorities and LGBT can still be left behind if for instance we have discrimination in the workplace or in lending. But if we make progress in those areas, then women, minorities and LGBT are more likely to share the an improving middle classe, or at least not suffer worse than a declining middle class.