It was my impression that dieticians recommend avoiding processed sugar because of the lack of nutrients, thus making it easy for a diet high in processed sugar to have too many calories and not enough nutrients. Also, that in people with a genetic predisposition to insulin resistance, diets high in sugar have been shown to be correlated with developing insulin resistance and diabetes.
I have never seen a professional dietician refer to 'sugary stuff' as 'bad for you'.
too many calories and not enough nutrients
That terminology has always confused me. What, sucrose is not a nutrient? Why not?
Not to mention that this is talking apples and oranges -- calories are a term from the physics-level description and nutrients are a term from the biochemistry-level description.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.