To the contrary, they’re a necessary component of a balanced, nutritious diet.
That being said, Americans generally eat way too much in the way of processed carbs and sugar.
On the other hand, I personally don’t ascribe to fad diets that call for cutting (or drastically reducing) entire food groups or macronutrient categories.
For me, such diets are sub-optimal from both a nutrition and sustainability standpoint because they physiologically and psychologically tend to lead to a sense of deprivation.
And while a case can be made for cutting down on refined carbs and sugar, I don’t buy diet fad claims that other types of commonly villanized food such as grain/gluten, dairy, and meat are fundamentally unhealthy. Absent special sensitivity (e.g., celiac, lactose intolerant, etc.) theres’s nothing inherently unhealthy about these foods. To the contrary, in moderation, they generally provide a net nutritional benefit.
Put another way, for most people, it’s better to focus on replacing less nutritious food with more nutritious food than to focus on cutting out entire food categories.