human brains are varied and there's no one single way a family should be structured. Kids need adults who are reliably there, keep them safe and love them, and there's a ton of different forms this can take.
Traditionalists are invested in how much any specific kind of parenting or family actually matters- even though data don't show this and we would expect some convergence in family structure across cultures to make optimal kids if this was the case. Human development is resilient.
Most data that shows bad effects of father absence is confounded by the fact that the kid also got genes from a dad who either couldn't stay or didn't choose to stay. Kids whose dads die in war or accidents don't have the same problems.