There may be some middle ground where CICO works, for some, but it's hardly a principle for one-size-fits-all.
You are presumably male, so you did not grow up with incessant articles about 1200 calorie diets, which proliferated in women's publications (and probably still do). Restrictive eating "guides" like this promote anorexia and other disorders. Less dramatically, one easily reaches a point of fatigue where the body starts to shut down to preserve energy. Cold, brain fog, etc., are frequent symptoms of too-low of a caloric intake.
The "machine" has a failure point and shuts down. It's not simple and linear.
Not everything about dietary guidelines is about weight loss. Indeed, the very concept of weight loss ignores that most humans want to preserve lean muscle mass, maintain hydration and bone density, while only losing excess fat. And yet we focus on the number on the scale, which is often useless. BMI was invented by a math guy, not a doctor. "lose weight!" is catchier, I guess, than "reduce body fat!"
Besides, for many, there are a plethora of benefits to reducing sugar. But all things must factor in your overall diet, lifestyle, etc.