Not all CI are stored as fat.
Not all CO are burned from fat.
Obesity specifically, is about excess fat, not bioavailable calories.
Imagine, as the article mentions, a person that has a daily calorie excess of exactly 10kcal per day from a potato chip. CICO with a 100% fat conversion dictates that person will gain 8lbs of pure fat every year.
Yet this isn't how it works in practice, so we need a better understanding of fat accumulation and loss if we want to address the crisis.
Any sufficiently drastic calorie deficit will result in weight loss, and eventually that loss will get to your fat stores. This is how the Twinkie diets works.
Most folks, myself included, would like to just stay at a healthy weight without thinking too much about 100 calories plus or minus their perceived BMR.
And for lots of folks that works, but clearly for an increasing majority, the 100kcal are stored as fat immediately, and the small 100kcal deficit doesn't burn the fat that was stored. Death by 1000 cuts.
Wouldn't it be interesting to discover why that might be and address it directly?