There are so many things I'd like to say on this thread, and I appreciate everyone's thoughtful responses.
Pupuce, does your nickname mean "papoose" by the way? Isn't that a word for a baby held in a sling, close to its mother? And is it also you that says GF advocates 20 minutes screaming and calls this a little bit? Is this meant to be ironic? And forgive me if it sound as if I'm having a go, but it sounds arbitrary in the extreme that you take the authority of your osteopath when he/she says crying is good for babies because of their "canals".
Why do mothers cry downstairs when their babies need them? Most people feel instinctively that it is wrong whatever the age of a child, to leave them to cry. People do it because there is something stronger than their instincts, which I think is peer pressure. And hence people accept these ideas about children trying it on.
I did discover with my 1st child that he needed stillness, so I agree with the not jiggling thing but I didn't leave him in isolation. I didn't always follow my instincts, for those who are interested and was experiencing some extreme outside events, bereavement and other major life events so I wouldn't like to give anyone advice based on my unusual experiences.
Babies thrive on closeness and most civilisations accept this without debate. Being kept close to their providers is how they experience love- it is life to them.If they are separated, denied access to that care at certain times, this gives them negative messages about life, to say the least.
I think so many of us have been subjected to this sort of deprivation as babies (it was the fashion in hospitals when I was born 40 years ago) that our natural instincts are damaged. The bigger problem is that because it is the norm everyone thinks its ok, not cruel or unnatural. But then, people used to think physical punishment was ok.