I do think my ex-wife and I could've agreed to 50/50 parenting and gotten a judge to sign off on our agreement. But she would never have given up her legal/strategic advantage. Perhaps she was doing what she thought was best for the children. Perhaps. But I think she was more self-centered than that, she was doing what she wanted, regardless of the impact on the kids.
While I don't blame my then-wife for "going for it" and asking for everything she wanted: the money, the house, the custody, I don't think she was thinking beyond her interests. And we can all cite studies about mothering and nurturing, but today, just as many modern studies show the dad is of equal importance in bringing up healthy kids.