Part of the problem, it seems to me, is that the word of the "experts" has filtered down into common knowledge. 100 years ago they called it modern, scientific parenting, now it has the weight of tradition behind it. It's not just doctors telling people what to do, it's mothers ( who learned to parent from Dr. Spock) telling their daughters, "Don't pick him up, you'll spoil him!"
I read somewhere ( I can't remember where) about an anthropologist who brought her baby with her to the village she was studying and had brought a portable crib for the baby to sleep in. The village women got together and gave her a stern talking to about how she was Doing It Wrong. Our mothers, grandmothers, neighbors, and coworkers are more likely to give us a lecture about the importance of putting baby on a schedule.