How could you possibly know that? I was #1 of 1 and I was a great mother. Most of my friends came from small families because our parents were just pulling themselves out of the great depression and couldn't afford more, but they knew they couldn't afford more and stuck with a small family. In my generation we mostly had small families and a lot of us raised wonderful and successful adults.
Raising a kid properly has little or nothing to do with burping and diapering. Proper diapering you learn the first time your little boy pees in your face and burping and spit up comes very quickly when you're clothes smell. Nurturing and caring and teaching them right from wrong you can't learn from a book.
You certainly know an awful lot about parenting don't you.