Same goes for my personal health pet peeve, obesity. Insurance will cover neither medically supervised weight loss nor bariatric surgery (at least not the whole thing). Yet, should I actually come down with diabetes, cancer, breathing problems, cellulitis, heart problems, high blood pressure, and more than ten other issues (there are about seventeen medical problems caused by obesity), THAT they'll actually cover.
In other words, they'll spend hundreds of thousands of dollars on all the health problems obesity causes, but they won't cover a patient getting rid of the cause of all those problems, obesity. In other words, they'll treat the symptoms, which are all those other diseases, but they won't treat the actual disease because they, in their infinite stupidity and idiocy, don't consider it a disease.