The problem is that even rigorous studies can be wrong, and it's not immediately obvious. This means people take intention into account as well.
A good example here, is how decades ago the FDA recommended people avoid eating fat (butter, lard, etc). This is how the fat-free movement started, and then it turned out that eating fat is actually benefitial for one's health. This misguided the public and food companies into substituting fat for sugars and carbs, which was very bad for public health.
Comments
The problem is that even rigorous studies can be wrong, and it's not immediately obvious. This means people take intention into account as well.
A good example here, is how decades ago the FDA recommended people avoid eating fat (butter, lard, etc). This is how the fat-free movement started, and then it turned out that eating fat is actually benefitial for one's health. This misguided the public and food companies into substituting fat for sugars and carbs, which was very bad for public health.