You may be seeing things a little black & white here. His advice was to listen to cravings & not control diet "too much". You seem to have interpreted this as "let here constantly eat all the junk food she wants & become obese."
I was goig off things like:
> don't control it.
> Let her eat what she wants.
> Cravings are there for a reason.
> If you control it too much, a shrivelled rag will pop out without any extra body fat.
> Children get sick and need some extra incase they lose it.
All of those comments err on the "extra weight is preferrable", but that's just not true. It's hard to have an underweight baby, it's very easy to have an overweight baby, and the risks of harm from overweight mother or baby need to be taken into account.
Strict diet control is likely to be more harmful than people realise. Many many people end up in hospital during pregnancy after controlling things very strictly. The amount of mothers following silly baby friendly diets results in a lot of faceplants and ICU trips and occasionally tears.
I was an NHS maternity ICU nurse for about 5 years and if your child is not healthy to begin with, the risks to mortality are off the scale if the baby is underweight. If you can't get them feeding pretty soon, they rely on metabolising that fat to get through anything in the first couple of weeks.
An overweight baby has some loose and non conclusive statistics tied to childhood obesity and maternal diabetes. With proper sizing scans, induction etc, the risks are minimal and the diabetes risk treatable (metformin, dietary changes).
Edit: batou again... also c-sections are something you want to avoid, having watched a couple, so you're right about a balance.
So, advising pregnant women to eat what they like, with no controls, increases risks and carries almost no benefit.
This is not suggesting that mothers should diet!
So there's not really any data.
Agree with your points for ref. It's all a compromise.