Palio/Keto, Vegan and the shunned balanced diet in the middle

Growing up in the '70s and '80s with an aunt who is a dietician, the conversation around the dinner table and at family get-togethers very often resolved to the balanced diet. I fondly remember she had a way to explain the food groups where the thumb was the protein, but the rest of the fingers are kinda foggy. The message was clear to eat a balanced diet. 

Fast-forward to today, and I am as confused as can be. Disclaimer, I not a dietician nor do I know anything about diets and have developed my bad habits over the years. I do however notice the cultural shift around me and the writing of this article is a way to make sense of the noise. I switch on Netflix and get messages of people miraculously being cured by only eating protein and fat, and others changing to a Vegan diet.