It's not that we as a society devalue childcare. We just don't live in an economy where it is safe for families to put all their eggs in one basket like that.
In post-WWII US, it was generally easy for fathers to find stable, lifelong careers with a low risk of layoffs and a low risk of an untimely death, which allowed families to thrive on single incomes. But that was an outlier, not the norm.
In most places and in most periods of history, mothers have had to work (sewing, gardening, spinning, knitting, brewing, laundering, midwifery, etc., etc.) because fathers have not had widespread access steady, well-paying, low-risk work. Unless she was independently wealthy, a mother who did not bring in income was playing a very risky game with her children's lives.
The biggest difference is that, today, most work must be done outside the home, which is very difficult for mothers. Childcare helps close the gender pay gap and is necessary for a fairer, less sexist society — at least until/unless our economy returns to primarily home-based work.
In the past extended family would usually live close by, so they could assist the mother inside the home. Today, both parents need to work outside the home, and family is usually too far away to assist.
That is very true. And even in cases where it was not true, families tended to have more children, so older siblings could help look after younger siblings while the family worked.