I've head many people express that, but I can't imagine it. I think people had different concepts of child-rearing then. Because no one was doing it differently.
But as for caring less: having a child is like cutting out a chunk of your physical heart, and using it to make this baby. The mere thought of harm to your child feels like torture. That's why us parents develop the no-sense-of-humor disadvantage regarding our kids.
I get your point, but I sort of disagree. Maybe "caring" in the abstract isn't the exact word for it, but I have friends who had 8, 10 or 11 mostly older siblings, and their parents definitely didn't give them as much thought or care as kids who had 0, 1 or 2 siblings. Like, they never coached a sports team, or helped with homework, or gave any impression that they were going to help pay for college, or attended school events. They kids basically on their own and partially raised by older siblings.
But as for caring less: having a child is like cutting out a chunk of your physical heart, and using it to make this baby. The mere thought of harm to your child feels like torture. That's why us parents develop the no-sense-of-humor disadvantage regarding our kids.