Nutrient density is not a measure of calories per mass or volume (energy density). This is what nutrient density means in the context of nutritional science:[1]

> The nutrient density standard, as defined by the FDA, is the ratio of the amount of beneficial nutrients relative to the food’s energy content per reference amount customarily consumed. The more nutrient-dense foods are those that contribute more beneficial nutrients than calories to the overall diet.

Fruits and vegetables generally have higher nutrient density than most other food categories:[2]

> As expected, we found that fruits and vegetables were nutrient-dense in relation to their energy content.

> However, the data unambiguously showed that fruits and vegetables were nutrient-rich in relation to the little energy that they provide. Although fruits and vegetables suffer when assessed on the calories/price ratio, they represent extremely good value when assessed using the nutrient density score and the nutrient to price ratio.

Sugar-sweetened beverages (SSBs), the most common source of added sugars, contributes to obesity and type 2 diabetes (T2D):[3]

> Consumption of SSBs has increased markedly across the globe in recent decades, tracking closely with the growing burdens of obesity. These beverages are currently the largest source of added sugar intake and the top source of daily energy in the US diet. The cumulative evidence from observational studies and experimental trials is sufficient to conclude that regular consumption of SSBs causes excess weight gain and these beverages are unique dietary contributors to obesity and T2D. Compelling evidence indicates that reducing SSBs will have significant impact on the prevalence of obesity and its related diseases, especially T2D.

Consuming at least 2 servings of fruit and 3 servings of vegetables per day (excepting fruit juices, starchy vegetables, and potatoes) is associated with lower mortality:[4]

> In the 2 prospective cohorts with many repeated measurements of diet and up to 30 years of follow-up, we observed that a higher intake of fruit and vegetables was associated with a lower risk of total mortality and cause-specific mortality in a nonlinear manner. Our analysis in the NHS and the HPFS and in a meta-analysis of 26 prospective cohort studies documented that intake of ≈5 servings of fruits and vegetables daily was associated with the lowest mortality, and higher intake was not associated with additional risk reductions in mortality. The thresholds of risk reduction in mortality were 2 servings daily for fruit intake and 3 servings daily for vegetable intake. Higher intakes of most subgroups of fruit and vegetables were inversely associated with mortality, whereas intakes of starchy vegetables, fruit juices, and potatoes were not associated with mortality.

And again, there is no evidence that fruits and whole grains in general are unhealthy in a balanced diet for most people.

Eating fruits is not equivalent to combining sodas with multivitamins. Fruits have fiber, antioxidants,[5] and other compounds that are absent from multivitamins.

[1] https://academic.oup.com/ajcn/article/82/4/721/4607427

[2] https://www.researchgate.net/publication/7446672_A_Nutrient_...

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5325726/

[4] https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.120.0...

[5] https://en.wikipedia.org/wiki/List_of_antioxidants_in_food