" You can't seriously imagine that a woman in 1910 who had 20 kids thought happily 'oh, but yay! "
I am in 40's, my Mum was born in 1928, my Nan in 1910. Ignoring that 1 in 10 women died in childbirth in the area in Liverpool (Walton) that she lived in and nearly every WC family lost at least one child, from a now curable illness , the average family size was 5 children.
My Grandad (who I knew) was from Italian origin. My bio GD was Native American, My Mums first DH was from Jamaica, My Dad from SA.
My Nan was in total shock at me being up and about three days after giving birth, women "lied in" for 10 days when she had hers and yes they had a support network of other women who would pitch in. As did all of the for mentioned relatives, the isolation that we now have, didn't happen.
How good and positive the support was emotionally, was a matter of luck. I agree that women were stuck in DV/poverty etc, but eradicating those didn't have to lead to where we are today.
I blame the 80's ethos of demonising LP's, rather than being about raising the quality of any type of family and concentrating on raising the quality of all types of relationships. There was much more a sense of shared values and goals before the Thatcher years, in my area (not speaking for London etc).
I would link how women are expected to parent, to sexism and the Patriarchy, Motherhood has always been an undervalued role.
Even in my childhood, I was probably one of the few children (of immigrant origin) that didn't have a large extended family around me.
If speaking "on average", or "in general" I agree with the OP.