The core idea is that a two income family is less financially resilient than a one income family because (a) the extra money goes to bid up housing prices (education, healthcare, etc.), and (b) if either partner has a setback, the family is at risk of bankruptcy.
Impacts of "women entering the workforce" have been relatively unexamined; one of them is that it frees up employers to practice other kinds of discrimination. For instance, many believe that black men held service jobs that got taken over by white women. You will get a woman on the Supreme Court but she will have been educated at Harvard. Pointedly, the supply of "people from high-class families" is doubled, so any bias towards hiring them can be indulged more freely.
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Some of these ideas have gotten traction in unexpected places. I was talking to a conservative friend the other day and he told me that "the gains of paying workers more would be eaten up by cost increases in housing, education and health care", which he didn't know was classic Elizabeth Warren!