The problem is that if it's just about obesity, you have to prove that cheaper treatments such as diet and exercise didn't work. That's not impossible to do, but it's hard and annoying even for people who really were trying. My doctor told me that you basically have to keep a detailed journal of your weight loss efforts for months on end.
Are GLP-1s so much more effective that we should make an exception to the general principle, maximizing healthcare resources by providing the cheapest effective treatment? I kinda think so, but I have a conflict of interest, and I can understand why others might think that money is better spent elsewhere.