This isn’t really complete or definitive. One thing many people ignore or hand-wave away is that there are large, unexplained differences in individual BMRs. BMRs are generally estimated by way of averages for a given weight or lean body mass, but those estimates can be wildly inaccurate for some individuals. This can represent an even larger error than calorie tracking errors, yet you didn’t even mention it. It is, unfortunately, very hard for an individual to get a truly accurate measurement of his or her BMR, so this is always going to be a blind spot in the energy balance equation.
Secondly, calories in is not a universal measure. Just because a package of food indicates an item has 100 calories, it does not mean that two different people who eat it will absorb precisely 100 calories of food energy from it. Everybody has digestive and metabolic idiosyncrasies, including differences in the human microbiome’s gut flora, the implications of which have only begun to be studied.
All that said, simple calorie tracking is still probably the most effective method for the largest number of people, but it’s not definitive or entirely universal. Anyone can start with estimates and try to refine further with data by tracking calorie intake and weight or other body outcomes as accurately as possible, but it’s also worth noting that there are unsafe ranges of calorie intakes above or below normal which it is inadvisable to try to sustain. If the basics don’t work, it’s probably better to seek professional medical advice instead of trying to shoehorn yourself into a purportedly definitive plan you saw on the internet.