The statement "Weightloss is calories in, calories out" is rather like "running a marathon is just running 100 meters and repeating it 420 more times". It's entirely true, but it's reductive beyond uselessness. Yes, if you burn more calories than you eat, you will always lose weight. And if you run 421, 100m stretches you've done a marathon. And both of those pieces of advice are completely useless to anyone trying to do it, and they can possibly even make things worse.

Managing satiety, breaking patterns, learning recipes that work for you, finding comfort without food, learning to say no to your immediate friends and family, dealing with binging, rewarding yourself without food, and many maaaaany other things are the tools people need to lose weight.

Calorie counting is useful and foundational, but you like my therapist used to say: "you can't live in a foundation". But, without a good foundation, you can't build a house either. If you switch your 5000 calorie fastfood diet for 5000 calories of fruit and vegetables, you're not going to lose weight.