Why do so many people believe they need a low carb diet to lose weight when it's actually a calorie deficit that causes them to?

I got in an argument with someone over a low carb diet vs calorie deficit for weight loss. They said eating low carb diet is the only way to lose weight and I told its the calorie decifit that causes people to lose weight.

They just would not believe me its the calorie deficit that causes the weight loss (law of thermodynamics) and kept saying only low carb diets work wtf.

I told them the only reason low carb works is becuase those people in a calorie dicifit now but still no they wouldn't believe me.

They really got fired up when I told them fruit, wholegrain bread, potatoes and sweet potatoes and brown rice are good for you. They said they are really bad for you but could not give a reason except its bad for your blood sugar. These carbs are loaded full fiber, vitamins and antioxidients ffs.
Why do so many people believe they need a low carb diet to lose weight when it's actually a calorie deficit that causes them to?
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