The no-fault divorce laws created this mess.
Shared Parenting = Marriage, for goodness sakes.
No fault divorce came about to to keep courts out of the business of trying to decide if two people asking for a divorce, and claiming infidelity, could then proceed. It was considered bad that two people wanting a divorce had to engage in "lying" to get one. Now look at the mess. No one stopped to consider that at least the TWO people wanted the divorce.
You forget to take into consideration those parents, and there are PLENTY out there, that never got married, who had children out of wedlock.
Not every custody battle is because of divorce.