Because it's CICO. Focusing on whole-foods can make you resistant to undesirable weight-gain, but losing substantial amounts of weight requires caloric restriction in some form or another. That isn't easy to adhere to, it needs to be done in whichever way is the most sustainable. Low-hanging fruit is to boost protein and fiber at higher-than-normal amounts for satiety.
All of the programs/diets that don't have you track calories are just tracking something else as a stand-in, obfuscating restriction. If you go low-carb and hit a wall, what are you going to do next, cut out negative carbs? If you go low-fat, will you cut out fat that's no longer there?
> The notion of two traps, a physical trap and a mental trap, comes from Allen Carr’s fantastic Easy Way To Stop Smoking. He states, quite convincingly, that there is a physical aspect to smoking (nicotine addiction) and a mental aspect to smoking (feeling that you need it).
I think Carr's perspective is very strong advice for kicking a bad habit. However, "emotional" and/or binge-eating may benefit from more targeted therapy.