I mean, it works in the sense that if you keep your calories out higher than your calories in you will lose weight.

Studies show that it's basically impossible to know your calories out without indirect calorimetry (and updating it regularly, no less, since your BMR + NEAT can vary significantly over time and in direct response to contemporary efforts to lose weight) -- and studies show that humans are dreadful at estimating their calories in.

So yes it works in a lab setting where your CI is pre-portioned in the form of milkshakes and your CO is measured via calorimetry. In reality though it makes people hella hungry and your hunger tends to increase in excess of changes to body weight.

Which is why the average weight regain after loss is 80% over 5 years.

So naturally it would seem we would look to develop ways to reduce our CI subconsciously. Enter GLP-1s. This is literally all they do. They reduce your hunger so your CI remains below your CO which studies show almost nobody can do without help.

Yes some people are genetically going to lose 200lbs and become the head of Weight Watchers in the same way that some people are going to win the olympic gold medal in swimming. That doesn't mean that you are going to win an olympic gold medal in swimming and it certainly doesn't mean that if the average person follows Phelps' training plan that they'll get an olympic gold medal in swimming.

Ultimately a treatment that works but nobody can actually maintain is a treatment that does not work. Hence GLP-1s. The question is why they are unable to keep their CI below CO. Not whether that’s how they lose weight.