If you want both parents to be independent, then (for the vast majority of people who are not very wealthy) of course both need to be employed or able to quickly become employed. Do you need a source for that?
Both of those take time, and that's time taken away from the children, which parents do not have in abundance. Do you need a source for that?
> both need to be employed or able to quickly become employed
Not particularly 'quickly', really.
Keeping it so both parents are able to be employed only requires corporate culture changes, and minor ones at that. The cost is very small and does not hurt children.
Most people don't have enough in savings to last more than half of a year without a job. I'd call that "quickly".
You could try to stop corporations from preferentially hiring people who have recent relevant experience, but I am not going to hold my breath on that.
A preference is fine, if it's in proportion to how much experience from the last couple years is actually worth over experience from 7 years ago. So maybe $5k less in initial salary.
The preference for someone having zero gaps in employment is extremely overrated, and giving many more people gaps in employment to disrupt that idea is great.
Both of those take time, and that's time taken away from the children, which parents do not have in abundance. Do you need a source for that?