hah! I like the quote.
Particularly when looking at glycogen metabolism, and also including things like fructose it's important to remember that the muscles and liver have a LIMITED ability to store carbohydrates as glycogen. Thus the more depleted your glycogen levels, the more carbohydrates one can handle. Hence the common recommendation on these forums to be relatively low-carb - but the more active folks who advocate higher carb intake are right too. It's when you're sedentary and take in too many carbs that the excess CHO that can't be stored get converted to fat en masse, spike blood sugar more, etc.
Our bodies are built to use a reasonable amount of carbohydrates(including a little bit of sugar) proportional to activity levels; They're not built to deal with giant milkshakes with 120 grams of sugar, gulped down in the span of 10 minutes while watching TV/sitting in the car. Most of our ancestors' sugar intake likely came from fresh fruit, which doesn't provide nearly the rush as most of the concentrated, refined carbohydrate sources we have around today. That giant milkshake has as much sugar as probably 3 pounds of berries, and far fewer nutrients.