Is it absurd? I think your statement is a bit too strong given what the OP has described: that seems a really painful experience for a parent. There is the pos

Is it absurd? I think your statement is a bit too strong given what the OP has described: that seems a really painful experience for a parent. There is the possibility that it is an evolutionary trait of some subset of the population: some children might not be able to sustain sleep training and others might be. So your statement is extreme too: it's entirely possible that some human beings are not made for that and others are. The only certainty we have is that humans need physical contact when they are babies, we don't know how much is enough from a scientific point though (and I doubt we would be able to do any experiment related to that ever again)