So the standard today is incompetence. An excellent lesson to learn early.
A can of Coke will not harm you in any meaningful way, but people do not have a can of Coke. They have 1+ cans of Coke every day. That absolutely will harm you.
I don't know how you took me to suggest someone eat only potatoes. I said a potato (anything, really) is a better source of calories than a Coke for pretty much all purposes. Pretty much no person anywhere needs an extra 39 g sugar with no nutrients at all in their diet.
Currently, 74% of the US is overweight or obese by BMI, which is likely an under-estimate of excess bodyfat: another 10% or so may have Normal Weight Obesity (i.e. skinnyfat), which is an understudied but increasingly recognized problem. Even without the issue of excess bodyfat, regularly creating large blood sugar spikes like that is not good for you. If nutritionists are working really hard to combat the idea that drinking literal sugar water is inappropriate for anyone to be doing with any regularity, then they are dropping the ball. In fact, you can find plenty of resources for the general public from the CDC about the deleterious effects of sugary beverages[0], and encouragement to reduce consumption of added sugars[1], specifically sugary beverages[2], the leading source of excess sugar in American diets.
Saying that candy is not food is not fear based nutrition. It is saying that candy is not food. We're not "afraid" of sugar or carbs; we just know "Skittles" aren't a food group, and have no purpose in any meal plan. Part of teaching kids how to be healthy is teaching them that we eat a variety of foods which each contribute different necessary nutrients with an appropriate calorie budget for our activity levels so that they understand how to one day develop their own plans. In that context, it ought to be obvious why our diet doesn't include pure sugar.
The competent thing to do is to teach people not to have emotional attachments to food. "This is not good for me (in fact injures me) and serves me no purpose, so I will not eat/drink it, and I will not buy it." That's it. The disorder is getting emotional about it and thinking it's somehow "damaging" to exclude junk food from one's diet.
[0] https://www.cdc.gov/nutrition/data-statistics/sugar-sweetene...
[1] https://www.cdc.gov/healthy-weight-growth/be-sugar-smart/ind...
[2] https://www.cdc.gov/healthy-weight-growth/rethink-your-drink...