The body should be able to figure out how to not eat in excess.
It's absolutely true that if you count calories, you can manage the input such that you lose weight. But it is not a solution for the vast majority of humanity.
> The body should be able to figure out how to not eat in excess.
Why? Evolutionarily, we've had very little time where constant surplus was the norm, and mostly are adapted to situations where surpluses are rare and temporary abd shortages common.
Fighting that is hard.
Sure, our bodies might become good at that if we survive for another million years with first world standards of living as the norm. But they aren’t now, for good—evolutionary—reasons.
It's absolutely true that if you count calories, you can manage the input such that you lose weight. But it is not a solution for the vast majority of humanity.