It's the role of science to be as accurate and precise as possible, and the vast majority - perhaps even all of them - fail to take into account enough variables to make it actually relevant; e.g. observational studies that target red meat being eaten don't usually differentiate from a healthy diet with red meat, high fat vs. low fat meat consumptions, nor account for what else a person is eating - e.g. ketogenic diet, if no sugars/carbs, etc.