I honestly cannot believe that playing with dolls turns little girls into good mothers later on, and that not playing with them, means that they have not "practised parenting skills" and are thus less likely to want, or to have children.
I grew up in the 1950s and 1960s. I played with dolls until I was 14 or 15, some of my friends did too, others didn't. Some of us were not able to have the children we dearly wanted, others did and were good mothers, others decided and held to it that they did not want children.
My sister was not interested in dolls, but was an excellent mother.
In Denmark today, children are playing with dolls - both girls and boys. In the 1970s most mothers and nursery school teachers actively discouraged little girls from playing with dolls, wearing pink frilly clothes etc. and wanted them to wear dungarees or jeans and play with cars. These were the years of Women's Lib at its most strident.
The children of the 1970s grew up into the parents of the children born in the 1990s - most of whom have had excellent mothers and fathers, although none of them, had like my generation any practical experience of small children before they had their own.
We babysat from the age of 12 (before that if we had younger siblings or cousins) and knew how rewarding and how exasperating small children could be. One of my cousins, who had a younger sister 14 years younger than herself, decided never to have children as although she loved them "they were too much hard work" an opinion she formed when her much loved sister was a baby.
There have always been many good parents and some bad ones. Sadly, this is not likely to change.
What has changed is that today we hear about the bad parents, where previous generations hid that fact as carefully as they hid the fact that there were wife-beaters, or horror of horrors, women who beat their husbands!