I am in complete agreement with RosiesMaw2.
The Royal Institution Christmas lectures are a joy, and I have learnt so much from them.
Whiff Nutrition is a young science, and much has still to be understood about it, especially now the abundance and availability of food in many countries far exceeds anything humans have experienced since they began, these on/off recommendations are inevitable, as in any science pushing its boundaries. This does not invalidate your advice that Just use your common sense and have a balanced diet is not correct, but the definition of what is a 'balanceed' diet, may well be open to interpretation and tweaking, given that from one part of the world to another, the idea of a balanced diet may be different.