Individual people have at best partial control over the decisions they make, and I don't think that any particular set of women, or even all women collectively,

Individual people have at best partial control over the decisions they make, and I don't think that any particular set of women, or even all women collectively, have complete control over the global fertility rate. To give just one example, some women may be infertile, despite their wishes. There is a coordination problem here, and even if all women could agree on the correct average global fertility level, and perfectly implement a fair quota system among themselves, I think there are other stakeholders who should be considered in that process: not just the men that might be involved in the raising of some of those children, but also the future generations of humanity that will only exist (or will exist in a very different environment) if the global fertility level goes outside a band of sustainability.