I would like to see an experiment where they took maybe 50 people, male and female, various ages and fitness levels. The first week they would normalize their diets so they were on a maintenance feeding plan. Then they would change the composition of their diets in various ways, spending a week with each modification. Then they would do something like the OP's plan for a week, adding a measured amount of calories of fat, carbs, or protein to see how it affected their weight and body composition.
Of course, if everybody put on exactly one pound per 3500 calories of anything consumed, that would prove the CICO howlers right. But I think the results would be much more nuanced, to say the least. Some people have efficient metabolisms. Some much less so. It would be great to see some known outliers in the experiment, too. A few people with thyroid issues, absolutely. And post-menopausal women, who are generally ignored in diet or exercise research.