Because hunger isn't just caused by the calorie bar maxing out, it's caused by your stomach's sensations.
If I could take a 2000 calorie pill and never eat, it would be uncomfortable for weeks and months, and I doubt it would ever be comfortable (though my stomach would adjust and shrink, this has its own negative effects).
I don't know a ton about nutrition, but I know for certain that when I eat foods that are less calorie dense, I feel full for longer, which helps me avoid cravings
I also fail to see the author's evidence against CICO, at least when it comes to weight loss. Sure, I won't go defining it as good or bad circularly, but I can say with certainty that calories determine your weight change, and if you eat fewer calories than you expend, then you *will* lose weight.