In fairness your post suggests you're someone who's given no serious thought or attention to the evidence around the impact of families not having enough money to cover basic living costs.
"We're not in the immediate post war period anymore and child benefit for that extra 3rd, 4th+ child in 2024 is not going to make diddly squat difference in reality."
Except the evidence - which you've obviously not looked at - shows it does.
It can be the difference between having to sit with the lights off one evening a week, or having electricity around the clock. It can be the difference between replacing a child's outgrown school shoes for a pair that fits, or sending them to school in tight shoes for a months.
BTW - the loss of benefits for a third child born after 2017 - that would put a family reliant on UC nearly £270 down a month. So a family that had one child born before 2017 and twins born after would get an extra £269 a month, compared to a family with three children where two were born in separate pregnancies after 2017. That's a big difference for people on low incomes. It's not an insignificant amount.
UC is intended to be a 'subsistence income' - ie, it's just enough to cover a family's basic needs. A family on UC with 3 children who don't get benefit for the third child by definition don't have enough income to meet their basic needs - and there are social, educational and health consequences for children growing up in a family which has insufficient income to meet basic needs.