Tl/dr: the campaign against sugar is not actually grounded on solid science - it's sort of a disinformation campaign to distract people from the other elephants in the room: rancid deodorized dietary oils, xeno-estrogens and other endocrine disrupters, etc...

People with a healthy metabolism can easily burn sugar for energy. Having a high metabolism increases the body's need for other nutrients, which are not present in white sugar. Sugar-rich foods, used in the context of a nutrient-dense diet, can be therapeutic.