This is one of those places where you can be entirely correct but entirely unhelpful. The problem is that calorie output is both a) non-constant (even your base metabolic rate changes over the course of your life, much less any lifestyle changes) and b) influenced by environment and physical condition (your calorie burn will change in response to environmental pressures, including caloric restriction and changing body fat content).
But you're right, this is a "technically correct" yet unhelpful answer.
That is demonstrably false.
If weight Z = X intake + Y energy expenditure, then you can reduce Z by keeping X the same and increasing Y.
Obviously diet has much more of an impact than exercise, but it's not true to say that the only way to lose weight is to eat less.
The linked article is a good explanation of why IF works; I don't disagree. But you can't say, "The key to weight loss is not to reduce calories"... because reducing calories is literally the only way you will ever lose weight.