I think the only takeaway is that babies vary a lot. Burping is best practice for the majority of babies; they'll end up really uncomfortable without it. It's just that there are some who don't need it and/or respond badly to it.

Most of the spit up problems we had happened when we tried to follow the pediatrician's orders and make her eat more. She knew when she was full, but she wasn't gaining weight quite as fast as they thought she should, so the doctor told me to overstuff her. That was... unwise.