I'm not aware of any valid poll that's been done that supports the assumption.
I don't see why it's necessary, because we're encouraging parents to come up co-operatively with what makes sense for them. The experience over the last 30 or 40 years has been that, as we move to more consensual processes outside of court, parents are increasingly sharing the parenting because they're not being encouraged to fight each other and they're not writing horrible affidavits about each other. They're meeting with a professional who's encouraging them to think about their children and to think about the harm.
If I can quickly just tell you, my key line that I give to parents as a mediator is to ask them to think about what story they want their children to tell their grandchildren about how they handled their separation. That tends to sober them down pretty quickly.