The calories in vs. calories out platitude has to go. Age, genetics, and other complicating factors play a huge role in who can lose weight, build muscle, and maintain. Medical science has little to offer for those outside some hypothetical mean. If "diet and exercise" don't work for you, you're out of luck.
CICO is fine. Those are all factors that affect the "calories out" part of the equation, they don't break it. The problem is education. Your average person sees things like "values based on a 2,000 calorie diet" and "you burn 100 calories per X minutes of walking" think that's how it works, a hard rule. Many have no understanding of how their own conditions (like age and genetics) warrant adjustment.
I've been "educated" by a couple of endocrinologists and dietitians. I've followed their directions to the letter, hired personal trainers, and still haven't seen any results.