Given the numerous ways people can lose bodyfat, is it only about calories or do macro's actually matter? Are we just splitting hairs about what actually works or can you achieve the same results with different macros. Is one scienticially better than the other?
For general purposes it probably doesn't matter much. Find what fits your lifestyle and go into a deficit.
For those in the game and who want to achieve long term results (5 even 10+ years of lifting from now on) I'm sure we can make changes that benefit our goals.
Warning: Incoming Broscience Professor
When I hear people talk about how it's mostly "calories in vs out" at the end of the day I can't help but notice how they almost never give thought to the ratio of fat:LBM gained or lost. In my mind, I see calories as the factor that pushes
weight gain or loss, but the adjustments we can make, supplements we can take, changes to training, meal timing, sleep etc as the optimization of body
composition. For example let's say you diet down to 180lbs/10% BF and now you are maintaining on a relatively active schedule and 2300 calories a day. Without changing your calorie intake there is probably a way to optimize how your body uses the calories you consume. Finding the optimal environment for you may take you 8% on the same calorie intake (yes, these numbers are arbitrary).
Given that our body is in a constant state of breaking down/using fat as energy, storing fat, building muscle, and also breaking down muscle, it would be best if we could find a way for our calories to be used as energy (for movement/exercise) and used in muscle building processes, while minimizing our calories being stored as fat and minimizing the muscle our body breaks down to maintain function.
I mostly see it this way because we know there are people who can keep a fairly lean and muscular body on a certain intake level, while other people will not be able to (and in the worst case, have poor body composition). I don't think that is even debatable. As an organism, some human bodies are incredibly gifted at being lean and muscular and others are not.
The debatable and kind of black box part then is the degree to which we can optimize it or if we are just fighting against our inherited bodies.