I think that all of this troll-calling of Bonsoir is out-of-order. Perhaps because I am extremely familiar the social milieu she lives in (DH is French, and many of our friends seem to be the same sort of Parisians that Bonsoir lives and socializes with).
It IS considered bad parenting in this circle to feed your children junk food. Here is an example: I was behind a mother and daughter in the cafe queue at the club we belong to (which has a large French membership). The daughter (about 8) wanted to order sausages and chips for lunch. The mother went on a tirade about how sausages as chips were disgusting, not real food, horrible for you, etc. The daughter caved in and meekly, to the satisfaction of the mum, said she would order a Salade Nicoise.
People ARE very conscious of weight and "la ligne". One of the reasons people were proud of Segolene Royal was because they had a candidate for President who was a middle aged mum who still looked fabulous in a bikini. Also, do people not recall the whole furore about Rachida Dati? She is hardly unusual in these circles (the slimness so soon after birth, not the jumping back FT into work at 10 days post C-section).
Another thing to keep in mind. Recently published results of an ongoing study on childhood obesity here in the UK found that parents were totally clueless if their child was overweight or not, also children who were overweight as kids in general ended up as overweight adults. I don't think it does children any good to brush aside any kind of weight gain. I think this has partially to do with parents themselves being overweight - it normalises being overweight and skews people's perception of normal weight.
HOWEVER, I also think it is counterproductive to make it such a focus with Weight Watcher style weigh ins. Probably better to just ever-so-slightly adjust diet and exercise without the child realising what is going on. Diets don't work - especially quick-loss ones
I also understand the annoyance Anna has with the suitcase full of relatively costly unsuitable (seasonally, not style wise as she has iterated and re-iterated) from someone who doesn't seem to be doing much towards the practical raising of her own kids. It probably just symbolises this woman's parenting style in Anna's eyes - which sounds more like a grandparent's style rather than a mum's (however, this might be due to the fact that this is all she feels she CAN contribute).
The rest, I can't comment on as I am not as familiar with her posts as other people.