My brother was on it for a bit (and should go on it again) and the thing he noted was that it makes it easy to not eat but it gives you no useful habits to keep that up because it's so easy.
Which makes sense. I still calorie count everything generally because I know I'll let myself creep portion sizes unchecked.
I think durable habits there are just hard honestly. I was losing weight when I was very strict about calorie counting and lived with a roommate who was on the same diet, but when I moved out and stayed with family my habits and intuition about safe foods didn't last long and temptation got me again.
It does make me think we're applying bandaids over some other issue with the available foods - it's hard to imagine that everyone 50 years ago was just much better about dieting and counting calories?
I don't think it's natural (in the sense of defining health) for adequate homeostasis to require special rituals and constant attention.